-8+15-4x=-3x(4x-5)

Solution for -8+15-4x=-3x(4x-5) equation:

-8+15-4x=-3x(4x-5)

We move all terms to the left:

-8+15-4x-(-3x(4x-5))=0

We add all the numbers together, and all the variables

-4x-(-3x(4x-5))+7=0


We calculate terms in parentheses: -(-3x(4x-5)), so:

-3x(4x-5)

We multiply parentheses

-12x^2+15x

Back to the equation:

-(-12x^2+15x)


We get rid of parentheses

12x^2-15x-4x+7=0

We add all the numbers together, and all the variables

12x^2-19x+7=0

a = 12; b = -19; c = +7;
Δ = b2-4ac
Δ = -192-4·12·7
Δ = 25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25}=5$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-19)-5}{2*12}=\frac{14}{24}
=7/12
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-19)+5}{2*12}=\frac{24}{24}
=1
$