SOLUTION: Solve by elimination: x+7y=30, 9x+6y=99 It really helps me to understand if I can See each step to solve this problem written out like in a math book. Thank you

Question 172825: Solve by elimination: x+7y=30, 9x+6y=99
It really helps me to understand if I can See each step to solve this problem written out like in a math book. Thank you
Found 2 solutions by Mathtut, checkley77:
Answer by Mathtut(3670) (Show Source): You can put this solution on YOUR website!
solving by elimination is simply adding or subtracting one equation from another
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with the intention of eliminating one of the variables.
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so lets line the equations up one under the other to have a better look at each variable.
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x+7y=30....eq 1
9x+6y=99....eq 2
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ok as you observe these equations we try to do the least amount of manipulation as possible to reach our goal.....we can either multiply eq 1 by -9 and add the equations together thus eliminating the x terms, or we could multiply eq 1 by - and eq 2 by -7 and add the two equations togethr to eliminate the y terms. I choose the first choice
:so -9(x+7y=30) equals -9x-63y=-270..so that is our revised eq 1. lets line them up again.
:
-9x-63y=-270
9x+ 6y=99
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so you see how if we add these two equations together that the x terms are eliminated because -9x+9x=0. We are left with -63y+6y=-270+99--->
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-57y=-171...dividing by -57 gives us
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.
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now we take y's value and plug it back into either original equation to solve for x I choose eq 1
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x+7(3)=30
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x+21=30
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:
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Answer by checkley77(12844) (Show Source): You can put this solution on YOUR website!
x+7y=30 multiply by -9 & add.
9x+6y=99
-9x-63y=-270
----------------
-57y=--171
y=-171/-57
y=3 ans.
x+7*3=30
x+21=30
x=30-21
x=9 ans.
Proof:
9*9+6*3=99
81+18=99
99=99

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