(2a+12)5a=180

Solution for (2a+12)5a=180 equation:

(2a+12)5a=180

We move all terms to the left:

(2a+12)5a-(180)=0

We multiply parentheses

10a^2+60a-180=0

a = 10; b = 60; c = -180;
Δ = b2-4ac
Δ = 602-4·10·(-180)
Δ = 10800
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{10800}=\sqrt{3600*3}=\sqrt{3600}*\sqrt{3}=60\sqrt{3}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(60)-60\sqrt{3}}{2*10}=\frac{-60-60\sqrt{3}}{20}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(60)+60\sqrt{3}}{2*10}=\frac{-60+60\sqrt{3}}{20}
$