60=40x-5x^2

Solution for 60=40x-5x^2 equation:

60=40x-5x^2

We move all terms to the left:

60-(40x-5x^2)=0

We get rid of parentheses

5x^2-40x+60=0

a = 5; b = -40; c = +60;
Δ = b2-4ac
Δ = -402-4·5·60
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-20}{2*5}=\frac{20}{10}
=2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+20}{2*5}=\frac{60}{10}
=6
$