SOLUTION: can you please help me solve by the addition-or-subtraction method: (((12a-5b=18 15a-5b=30)))

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Question 154843This question is from textbook Algebra structure and method book 1
: can you please help me solve by the addition-or-subtraction method: (((12a-5b=18 15a-5b=30))) This question is from textbook Algebra structure and method book 1

Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
12a-5b=18
15a-5b=30 SUBTRACT
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-3A=-12
A=-12/-3
A=4 ANSWER.
12*4-5B=18
48-5B=18
-5B=18-48
-5B=-30
B=-30/-5
B=6 ANSWER.
PROOF:
15*4-5*6=30
60-30=30
30=30