Question 531520
You have to remember to do the same thing to both sides of the equation, whatever that might be.
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10a-37=6a+51
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Subtract 6a from both sides.  That will cancel the 6a on the right side, so that all 'a' terms are on the left side.
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4a -37 = 51
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Add 37 to both sides.  That will cancel the -37 on the left.
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4a = 88
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Divide both sides by 4.  That will eliminate the coefficient on 'a'.
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a = 22
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Always check the solution to make sure it is the correct answer. 
Substitute 22 for 'a' and check the values.
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10*22 -37 = 220 -37 = 183
6*22 + 51 = 132 + 51 = 183
183 = 183
Correct.
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Answer:  a = 22
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P.S. In the old days, teachers talked about "moving" factors from one side of the equation to the other.  After years of confusion and frustration, I ran into a math teacher who explained that you have to do the same time to both sides.  You cannot just "move" anything from one side to the other.