(2x)(5x+40)=180

Solution for (2x)(5x+40)=180 equation:

(2x)(5x+40)=180

We move all terms to the left:

(2x)(5x+40)-(180)=0

We multiply parentheses

10x^2+80x-180=0

a = 10; b = 80; c = -180;
Δ = b2-4ac
Δ = 802-4·10·(-180)
Δ = 13600
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:

$\sqrt{\Delta}=\sqrt{13600}=\sqrt{400*34}=\sqrt{400}*\sqrt{34}=20\sqrt{34}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(80)-20\sqrt{34}}{2*10}=\frac{-80-20\sqrt{34}}{20}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(80)+20\sqrt{34}}{2*10}=\frac{-80+20\sqrt{34}}{20}
$