(-12a+20)a=3

Solution for (-12a+20)a=3 equation:

(-12a+20)a=3

We move all terms to the left:

(-12a+20)a-(3)=0

We multiply parentheses

-12a^2+20a-3=0

a = -12; b = 20; c = -3;
Δ = b2-4ac
Δ = 202-4·(-12)·(-3)
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-16}{2*-12}=\frac{-36}{-24}
=1+1/2
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+16}{2*-12}=\frac{-4}{-24}
=1/6
$