12а-3в÷12а+3в при= -3/4 в =-5/6

To simplify the expression 12а-3в÷12а+3в, we substitute в with -5/6.

12а - 3(-5/6) ÷ 12а + 3(-5/6)

Next, simplify the multiplication and division.

12а + 5/2 ÷ 12а - 5/2

Since we have a division, we can rewrite the expression as a multiplication by the reciprocal.

(12а + 5/2) * (12а - 5/2)

Now, simplify the multiplication of the binomials.

144а^2 - 25/4

So, the simplified expression is 144а^2 - 25/4.