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(1/4)*x-((5/8)*x) = 30-42 // - 30-42
(1/4)*x-((5/8)*x)-30+42 = 0
(1/4)*x+(-5/8)*x-30+42 = 0
12-3/8*x = 0 // - 12
-3/8*x = -12 // : -3/8
x = -12/(-3/8)
x = 32
x = 32
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