The sum of 36 and twice the first number is equal to three time the second number.
if you subtract the first number from the second number and halve the result, you get 8

So 36+2x=3y
-x+y=z
z/2=8
(y-x)/2=8
first you want to find what x or y is by isolating one of them
so (y-x)/2=8
multiply both sides by 2
y-x=16
subtract 16 from both sides
y-x-16=0
add x to both sides
y-16=x
subtitute into first equation
36+2(y-16)=3y
distrubute
36+2y-32=3y
add like terms
4+2y=3y
subtract 2y from both sides
4=y
subutue into second equation
(4-x)/2=8
multiply both sides by 2
4-x=16
add x to both sides
4=16+x
subtract 16 from both sides
-12=x
y=4