Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemandStart anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 563 reviewsTarget Test Prep

Given 2x + y + z = 3 and 5x + 3y + z = 8, what is the

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Legendary Member
Posts: 2276
Joined: Sat Oct 14, 2017 6:10 amFollowed by: 3 members
by VJesus12 » Mon Mar 19, 2018 3:50 am
Given

2x + y + z = 3
and

5x + 3y + z = 8,

what is the value of x + y - z ?

A. -2
B. -1
C. 0
D. 1
E. 2

The OA is E.

How can I know the value of x + y - z if I know just two equations? Can any expert give me some help here? Thanks in advanced.
Top
Join the discussion
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Mon Mar 19, 2018 4:10 am
VJesus12 wrote:Given

2x + y + z = 3
and

5x + 3y + z = 8,

what is the value of x + y - z ?

A. -2
B. -1
C. 0
D. 1
E. 2.
If we multiply 2x+y+z=3 by 2, we get:
4x+2y+2z=6.
If we subtract the equation in blue from 5x+3y+z=8, we get:
(5x+3y+z) - (4x+2y+2z) = 8-6
x+y-z = 2.

The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16206
Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members
Location: Vancouver, BC
Thanked: 5254 times
GMAT Score:770

by Brent@GMATPrepNow » Mon Mar 19, 2018 6:05 am
VJesus12 wrote:Given

2x + y + z = 3
and
5x + 3y + z = 8,

What is the value of x + y - z ?

A. -2
B. -1
C. 0
D. 1
E. 2
Another approach is to look for values of x, y and z that satisfy BOTH equations (2x + y + z = 3 and 5x + 3y + z = 8).
One set of values is x = 1, y = 1 and z = 0 (there are infinitely many sets of values that satisfy both equations)

What is the value of x + y - z ?
x + y - z = 1 + 1 - 0 = 2

Answer: E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
User avatar
GMAT Instructor
Posts: 1462
Joined: Thu Apr 09, 2015 9:34 amFollowed by: 22 members
Location: New York, NY
Thanked: 39 times

by Jeff@TargetTestPrep » Tue Mar 20, 2018 4:03 pm
VJesus12 wrote:Given

2x + y + z = 3
and

5x + 3y + z = 8,

what is the value of x + y - z ?

A. -2
B. -1
C. 0
D. 1
E. 2
We can multiply the first equation by -2, and we have:

-4x - 2y - 2z = -6

Adding the above equation with the equation 5x + 3y + z = 8, we have:

x + y - z = 2

Answer: E

Jeffrey Miller
Head of GMAT Instruction
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
Top
Join the discussion
Legendary Member
Posts: 2214
Joined: Fri Mar 02, 2018 2:22 pmFollowed by: 5 members

by deloitte247 » Fri Mar 23, 2018 11:23 pm
$$2x+y+z=3---\left(i\right)$$
$$5x+3y+z=8---\left(ii\right)$$
$$mutiply\ eqn\ \left(i\right)\ by\ \left(2\right)$$
$$\left(2x\cdot2\right)+\left(2\cdot y\right)+\left(2\cdot z\right)=2\cdot3$$
$$4x+2y+2z=6---\left(iii\right)$$
Subtract eqn (iii) from (ii)
$$5x+3y+z=8---\left(ii\right)$$
$$4x+2y+2z=6---\left(iii\right)$$
$$we\ have\ x+y-z=2$$
The correct option is E
Top
Join the discussion