Answer:
v=-1
Explanation:
15x - 21v = 51---------(mutiply by 3) (Equaltion-1)
-15x -10v = -20 ------- (mutiply by -5) (Equation-20
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-31v=31 (Cancel 15x and 15x because Equation 1 15x is positive and equation 2 15x is netgative.
v=-1