Question

Use guess-and-check to find two numbers that have the sum of 10 and a difference of 6.

Answer 1

10=x-6 so then 10=6+4

Answer 2

x+y=10
x-y=6
SOLVE FOR x and y

Answer 3

It's guess and check or most commonly called "trial and error", you're not meant to solve it as a system of equations.

Answer 4

But then again, that's for future reference when doing questions without trial and error.