Explanation:
Let's take the numbers as m and n and classify the info
m+n=8
m-n=4
So solving the sums Simultaneously you can get
2n=4
n=2
Substituting this value gives
2+m=8
m=6
Inorder to check if your answers are valid add them to the equations
6+2=8✅
6-2=4✅
Therefore the answers are valid