Question 282175
x-y=25
x=3y+4
(3y+4)-y=25
3y-y=25-4
2y=21
y=21/2
y=10.5
x-10.5=25
x=25+10.5
x=35.5
Proof:
35.5=3*10.5+4
35.5=31.5+4
35.5=35.5