202.5=36t-0.8t^2

Solution for 202.5=36t-0.8t^2 equation:

202.5=36t-0.8t^2

We move all terms to the left:

202.5-(36t-0.8t^2)=0

We get rid of parentheses

0.8t^2-36t+202.5=0

a = 0.8; b = -36; c = +202.5;
Δ = b2-4ac
Δ = -362-4·0.8·202.5
Δ = 648
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{648}=\sqrt{324*2}=\sqrt{324}*\sqrt{2}=18\sqrt{2}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-36)-18\sqrt{2}}{2*0.8}=\frac{36-18\sqrt{2}}{1.6}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-36)+18\sqrt{2}}{2*0.8}=\frac{36+18\sqrt{2}}{1.6}
$