36=18.5x+x^2

Solution for 36=18.5x+x^2 equation:

36=18.5x+x^2

We move all terms to the left:

36-(18.5x+x^2)=0

We get rid of parentheses

-x^2-18.5x+36=0

We add all the numbers together, and all the variables

-1x^2-18.5x+36=0

a = -1; b = -18.5; c = +36;
Δ = b2-4ac
Δ = -18.52-4·(-1)·36
Δ = 486.25
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{-(-18.5)-\sqrt{486.25}}{2*-1}=\frac{18.5-\sqrt{486.25}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18.5)+\sqrt{486.25}}{2*-1}=\frac{18.5+\sqrt{486.25}}{-2}
$