Help me solve this

Question

The sum of two numbers is 40 and their difference is 10.

what are the two numbers?

There need to be a big number and a small number

Answer 1

15 and 25

they sum to 40

their difference is 10

x+y = 40

x-y = 10 add the two equations to eliminate one variable

2x = 50

x = 50/2 = 25

y =40-25 = 15