Use the elimination method to solve the system

Use the elimination method to solve:
6a - b = 3
b + 4a = 17

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First, re-arrange the equations to line up the a’s, b’s, and the constant terms.

6a - b = 3
b + 4a = 17

6a - b = 3 {first original equation}
4a + b = 17 {re-arranged second original equation}
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10a = 20 {added the two equations together}
a = 2 {divided each side by 10}

Substitute 2, in for a, into one of the two equations.
b + 4a = 17 {second original equation}
b + 4(2) = 17 {substituted 2, in for a, into second original equation}
b + 8 = 17 {multiplied 4 by 2}
b = 9 {subtracted 8 from each side}

a = 2 and b = 9

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