4800=x^2-70x+3000

Solution for 4800=x^2-70x+3000 equation:

4800=x^2-70x+3000

We move all terms to the left:

4800-(x^2-70x+3000)=0

We get rid of parentheses

-x^2+70x-3000+4800=0

We add all the numbers together, and all the variables

-1x^2+70x+1800=0

a = -1; b = 70; c = +1800;
Δ = b2-4ac
Δ = 702-4·(-1)·1800
Δ = 12100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{12100}=110$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(70)-110}{2*-1}=\frac{-180}{-2}
=+90
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(70)+110}{2*-1}=\frac{40}{-2}
=-20
$