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x in (-oo:+oo)
-3/40 = x+4/5 // - x+4/5
-x-3/40-(4/5) = 0
-x-3/40-4/5 = 0
-x-7/8 = 0 // + 7/8
-x = 7/8 // * -1
x = -7/8
x = -7/8
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