(X+5)(3x)=180

Solution for (X+5)(3x)=180 equation:

(X+5)(3X)=180

We move all terms to the left:

(X+5)(3X)-(180)=0

We multiply parentheses

3X^2+15X-180=0

a = 3; b = 15; c = -180;
Δ = b2-4ac
Δ = 152-4·3·(-180)
Δ = 2385
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:

$\sqrt{\Delta}=\sqrt{2385}=\sqrt{9*265}=\sqrt{9}*\sqrt{265}=3\sqrt{265}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-3\sqrt{265}}{2*3}=\frac{-15-3\sqrt{265}}{6}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+3\sqrt{265}}{2*3}=\frac{-15+3\sqrt{265}}{6}
$