If x and y are positive integers and x = 3y, what is the value of x ?

[BTGModeratorVI]

If x and y are positive integers and x = 3y, what is the value of x ?

(1) y < 10
(2) x < 5

Answer: B
Source: Princeton Review

[Brent@GMATPrepNow]

If x and y are positive integers and x = 3y, what is the value of x ?

(1) y < 10
(2) x < 5

Answer: B
Source: Princeton Review

Given: x and y are positive integers and x = 3y

Target question: What is the value of x?

Statement 1: y < 10
If x = 3y, we can divide both sides by 3 to get: y = x/3
Substitute to get: x/3 < 10
Multiply both sides by 3 to get: x < 30
Statement 1 is NOT SUFFICIENT

Statement 2: x < 5
Substitute to get: 3y < 5
Divide both sides by 3 to get: y < 5/3
Since we're told y is a POSITIVE INTEGER, it must be the case that y = 1
Since x = 3y, we can be certain that x = 3
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

Cheers,
Brent