math
posted by asia on .
how would i use substitution for the equations x+y=56 and x+(3y)=56

Isolate x or y in either equation and then subsitute it in to the other equation.
x+y=56
x=56y
Subsitute into the other equation:
Since x=56y, the other equation becomes (56y)+3y=56
56+2y=56 subtract 56 from both sides
2y=0
y=0/2
y=0
then x must be 56