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May 6, 2016

# Homework Help: math

Posted by asia on Thursday, January 21, 2010 at 10:58pm.

how would i use substitution for the equations x+y=56 and x+(3y)=56
• math - ALan, Thursday, January 21, 2010 at 11:20pm

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