SOLUTION: Solve each system using elimination. 3x+6y=42 -7x+8y= -109

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Question 713608: Solve each system using elimination.

3x+6y=42
-7x+8y= -109
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
3x+6y=42 multiply by 4
-7x+8y=-109 multiply by -3 & add.
12x+24y=168
21x-24y=327
-------------------------
33x=495
x=495/33
x=15 ans.
3*15+6y=42
45+6y=42
6y=42-45
6y=-3
y=-3/6
y=-.5 ans.
Proof:
-7*15+8(-.5)=-109
-105-4=-109
-109=-109