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3*x+1/2 = (-1/5)*x-(123/10) // - (-1/5)*x-(123/10)
3*x-((-1/5)*x)+1/2+123/10 = 0
3*x+(1/5)*x+1/2+123/10 = 0
16/5*x+64/5 = 0 // - 64/5
16/5*x = -64/5 // : 16/5
x = -64/5/16/5
x = -4
x = -4
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