-5(2x-5)3x-5=7

Solution for -5(2x-5)3x-5=7 equation:

-5(2x-5)3x-5=7

We move all terms to the left:

-5(2x-5)3x-5-(7)=0

We add all the numbers together, and all the variables

-5(2x-5)3x-12=0

We multiply parentheses

-30x^2+75x-12=0

a = -30; b = 75; c = -12;
Δ = b2-4ac
Δ = 752-4·(-30)·(-12)
Δ = 4185
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4185}=\sqrt{9*465}=\sqrt{9}*\sqrt{465}=3\sqrt{465}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(75)-3\sqrt{465}}{2*-30}=\frac{-75-3\sqrt{465}}{-60}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(75)+3\sqrt{465}}{2*-30}=\frac{-75+3\sqrt{465}}{-60}
$