What is the value of n in the equation: - 25 + 19 + n = s ?

[BTGmoderatorDC]

What is the value of n in the equation: - 25 + 19 + n = s ?

(1) s = 2
(2) n/s = 4

OA D

Source: Official Guide

[Brent@GMATPrepNow]

What is the value of n in the equation: -25 + 19 + n = s ?

(1) s = 2
(2) n/s = 4

Given: -25 + 19 + n = s
Simplify: -6 + n = s
Add 6 to both sides to get: n = s + 6

Target question: What is the value of n?

Statement 1: s = 2
We already know that n = s + 6
Replace s with 2 to get: n = 2 + 6 = 8
The answer to the target question is n = 8
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: n/s = 4
Multiply both sides by s to get: n = 4s
Divide both sides by 4 to get: n/4 = s

We already know that n = s + 6
Replace s with s with n/4 to get: n = n/4 + 6
Multiply both sides by 4 to get: 4n = n + 24
Subtract n from both sides to get: 3n = 24
Solve, n = 8
The answer to the target question is n = 8
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: D

Cheers,
Brent

[GMATGuruNY]

What is the value of n in the equation: - 25 + 19 + n = s ?

(1) s = 2
(2) n/s = 4

What do we want?
The value of n.
Before we look at the statements, what do we have?
A linear equation with two variables (n and s).
To answer the question stem, what do we need?
Another linear equation with one or both of the variables.

Each statement gives us what we need and thus is SUFFICIENT.

The correct answer is D.