(25x-10)(15x+2)+28=180

Solution for (25x-10)(15x+2)+28=180 equation:

(25x-10)(15x+2)+28=180

We move all terms to the left:

(25x-10)(15x+2)+28-(180)=0

We add all the numbers together, and all the variables

(25x-10)(15x+2)-152=0

We multiply parentheses ..

(+375x^2+50x-150x-20)-152=0

We get rid of parentheses

375x^2+50x-150x-20-152=0

We add all the numbers together, and all the variables

375x^2-100x-172=0

a = 375; b = -100; c = -172;
Δ = b2-4ac
Δ = -1002-4·375·(-172)
Δ = 268000
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:

$\sqrt{\Delta}=\sqrt{268000}=\sqrt{400*670}=\sqrt{400}*\sqrt{670}=20\sqrt{670}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-100)-20\sqrt{670}}{2*375}=\frac{100-20\sqrt{670}}{750}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-100)+20\sqrt{670}}{2*375}=\frac{100+20\sqrt{670}}{750}
$