The sum of 2 numbers is ten and their difference is 8. What is the answer?

Question

So I got this question on prodigy a couple of weeks ago and I couldn' t understand it.

Answer 1

The 2 numbers are n and m.

n + m = 10

n - m = 8

Add the 2 equations and get

2n = 18

n = 9

m = 10 - n = 10 - 9 = 1

Test the answer.