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7*x-((6/7)*x)+8 = 51 // - 51
7*x-((6/7)*x)-51+8 = 0
(-6/7)*x+7*x-51+8 = 0
43/7*x-43 = 0 // + 43
43/7*x = 43 // : 43/7
x = 43/43/7
x = 7
x = 7
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