The value of two numbers if their sum is 12 and their difference is 4. write a system of equation and find the two numbers

x+y=12

x-y=4

Then you solve:

x+y=12

 -y   -y

x=12-y

x-y=4

  +y  +y

x=4+y

4+y=12-y

  +y      +y

4+2y=12

-4        -4

2y=8

divide both sides by 2 to isolate y

y=4

Plug it into one of the equations

x+4=12

 -4    -4

x=8

entering that problem on the tube might get you an answer