Question 1060739
Same problem, different numbers.
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substitution method. 
 -5x-8y=17
 2x-7y=-17
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 2x-7y=-17 --> x = (7/2)y - 17/2
 Sub for x in the 1st eqn.
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 -5x-8y=17
 -5*((7/2)y - 17/2) - 8y = 17
 Multiply by 2 to eliminate fractions.
 -5*(7y - 17) - 16y = 34
 -35y + 85 - 16y = 34
 -51y = -51
 y = 1
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 x = (7/2)y - 17/2
 x = -5