Question

y=x/4+4

x=21.5+7y/8

Answer 1

it's usually easier if yu clear fractions. So,multiply #1 by4, #2 by 8:

4y = x + 16
8x = 172 + 7y

now you can rearrange things as you wish:

-x + 4y = 16
8x - 7y = 172

solution: (32,12)