3750=-x^2+135x-300

Solution for 3750=-x^2+135x-300 equation:

3750=-x^2+135x-300

We move all terms to the left:

3750-(-x^2+135x-300)=0

We get rid of parentheses

x^2-135x+300+3750=0

We add all the numbers together, and all the variables

x^2-135x+4050=0

a = 1; b = -135; c = +4050;
Δ = b2-4ac
Δ = -1352-4·1·4050
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-135)-45}{2*1}=\frac{90}{2}
=45
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-135)+45}{2*1}=\frac{180}{2}
=90
$