25x-2.5x^2=60

Solution for 25x-2.5x^2=60 equation:

25x-2.5x^2=60

We move all terms to the left:

25x-2.5x^2-(60)=0

a = -2.5; b = 25; c = -60;
Δ = b2-4ac
Δ = 252-4·(-2.5)·(-60)
Δ = 25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25}=5$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(25)-5}{2*-2.5}=\frac{-30}{-5}
=+6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(25)+5}{2*-2.5}=\frac{-20}{-5}
=+4
$