7x(x+20)=60

Solution for 7x(x+20)=60 equation:

7x(x+20)=60

We move all terms to the left:

7x(x+20)-(60)=0

We multiply parentheses

7x^2+140x-60=0

a = 7; b = 140; c = -60;
Δ = b2-4ac
Δ = 1402-4·7·(-60)
Δ = 21280
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:

$\sqrt{\Delta}=\sqrt{21280}=\sqrt{16*1330}=\sqrt{16}*\sqrt{1330}=4\sqrt{1330}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(140)-4\sqrt{1330}}{2*7}=\frac{-140-4\sqrt{1330}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(140)+4\sqrt{1330}}{2*7}=\frac{-140+4\sqrt{1330}}{14}
$