[tex]\\
\text{Consider the equation}\\
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7a-2b=5a+b\\
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\text{to solve for a, we will first add 2b both sides. so we get}\\
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7a-2b+2b=5a+b+2b\\
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\Rightarrow 7a=5a+3b\\
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\text{now subtract 5a both sides. so we have}\\
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7a-5a=3b\\
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\Rightarrow 2a=3b\\
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\text{divide 2 both sides to get}\\
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\Rightarrow a=\frac{3b}{2}[/tex]
Hence the value of a is: 3b/2
