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(3*y-(12*x)+15)/3+7*y = 0
(3*y-12*x+15)/3+7*y = 0
(3*y-12*x+15)/3+(3*7*y)/3 = 0
3*y-12*x+3*7*y+15 = 0
24*y-12*x+15 = 0
(24*y-12*x+15)/3 = 0
(24*y-12*x+15)/3 = 0 // * 3
24*y-12*x+15 = 0
24*y-12*x+15 = 0 // - 24*y+15
-12*x = -(24*y+15) // : -12
x = (-(24*y+15))/(-12)
x = (24*y+15)/12
x = (24*y+15)/12
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