Question

the sum of two numbers is 26 and their difference is 20.find each of the numbers.

Answer 1

23 and 3
23 + 3 = 26 and 23 - 3 = 20

Answer 2

(1) x+y= 26 
 (2 ) x-y= 20 from here we can find : x= 20+y
We replace the ''x'' we found from (2) to the (1)
20+y+y=26
2y= 26-20
2y=6
y=3
x= 20+y = 23
Prove: 23+3 = 26 and 23-3 = 20