(5b-b)(12-5b)=0

Solution for (5b-b)(12-5b)=0 equation:

(5b-b)(12-5b)=0

We add all the numbers together, and all the variables

(+4b)(-5b+12)=0

We multiply parentheses ..

(-20b^2+48b)=0

We get rid of parentheses

-20b^2+48b=0

a = -20; b = 48; c = 0;
Δ = b2-4ac
Δ = 482-4·(-20)·0
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(48)-48}{2*-20}=\frac{-96}{-40}
=2+2/5
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(48)+48}{2*-20}=\frac{0}{-40}
=0
$