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a in (-oo:+oo)
a-(5*(a-(2/4)))-(4/5) = 3*a+12/2 // - 3*a+12/2
a-(5*(a-(2/4)))-(3*a)-(4/5)-(12/2) = 0
a-5*(a-1/2)-3*a-4/5-6 = 0
(-5*5*(a-1/2))/5+(5*a)/5+(-3*5*a)/5-4/5+(-6*5)/5 = 0
5*a-5*5*(a-1/2)-3*5*a-6*5-4 = 0
25/2-20*a-15*a-30-4 = 0
25/2-35*a-30-4 = 0
17/2-35*a-30 = 0
-35*a-43/2 = 0
(-35*a-43/2)/5 = 0
(-35*a-43/2)/5 = 0 // * 5
-35*a-43/2 = 0
-35*a-43/2 = 0 // + 43/2
-35*a = 43/2 // : -35
a = 43/2/(-35)
a = -43/70
a = -43/70
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