BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

If x and y are both positive integers, how much greater is x

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 2898
Joined: Thu Sep 07, 2017 2:49 pmFollowed by: 5 members
Thanked: 6 times
by Vincen » Sat Oct 21, 2017 5:46 pm
If x and y are both positive integers, how much greater is x than y?

(1) x + y = 20
(2) x = y^2

The OA is C.

How can I use both statements together to get an answer? Experts, may you help me?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 amFollowed by: 34 members
Location: Grand Central / New York
Thanked: 470 times

by Jay@ManhattanReview » Tue Oct 24, 2017 5:46 am
Vincen wrote:If x and y are both positive integers, how much greater is x than y?

(1) x + y = 20
(2) x = y^2

The OA is C.

How can I use both statements together to get an answer? Experts, may you help me?
We have to find out the value of x - y.

(1) x + y = 20

Certainly insufficient. If, for example, x = 1 and y = 19, then x - y = 18; however, if x = 2 and y = 18, then x - y = 16. No unique value. Insufficient.

(2) x = y^2

Certainly insufficient.

(1) and (2) combined:

y^2 + y = 20

y^2 + y - 20 = 0

y^2 + 5y - 4y - 20 = 0

y(y+5) -4(y+5)=0

(y+5)(y-4)=0

=> y = -5 or 4.

Since y is positive, y = 4.

=> x = y^2 = 4^2 = 16

=> x - y = 16 - 4 = 12. Sufficient.

The correct answer: C

Hope this helps!

-Jay

Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide
_________________
Manhattan Review GMAT Prep

Locations: New York | New Delhi | Seoul | Cairo | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 amFollowed by: 34 members
Location: Grand Central / New York
Thanked: 470 times

by Jay@ManhattanReview » Tue Oct 24, 2017 5:48 am
Vincen wrote:If x and y are both positive integers, how much greater is x than y?

(1) x + y = 20
(2) x = y^2

The OA is C.

How can I use both statements together to get an answer? Experts, may you help me?
We have to find out the value of x - y.

(1) x + y = 20

Certainly insufficient. If, for example, x = 1 and y = 19, then x - y = 18; however, if x = 2 and y = 18, then x - y = 16. No unique value. Insufficient.

(2) x = y^2

Certainly insufficient.

(1) and (2) combined:

y^2 + y = 20

y^2 + y - 20 = 0

y^2 + 5y - 4y - 20 = 0

y(y+5) -4(y+5)=0

(y+5)(y-4)=0

=> y = -5 or 4.

Since y is positive, y = 4.

=> x = y^2 = 4^2 = 16

=> x - y = 16 - 4 = 12. Sufficient.

The correct answer: C

Hope this helps!

-Jay

Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide
_________________
Manhattan Review GMAT Prep

Locations: New York | New Delhi | Seoul | Cairo | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1