(X-16.5)(c-109)=0

Solution for (X-16.5)(c-109)=0 equation:

(X-16.5)(X-109)=0

We multiply parentheses ..

(+X^2-109X-16.5X+1798.5)=0

We get rid of parentheses

X^2-109X-16.5X+1798.5=0

We add all the numbers together, and all the variables

X^2-125.5X+1798.5=0

a = 1; b = -125.5; c = +1798.5;
Δ = b2-4ac
Δ = -125.52-4·1·1798.5
Δ = 8556.25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-125.5)-\sqrt{8556.25}}{2*1}=\frac{125.5-\sqrt{8556.25}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-125.5)+\sqrt{8556.25}}{2*1}=\frac{125.5+\sqrt{8556.25}}{2}
$