200=-16t^2+80t+180.4

Solution for 200=-16t^2+80t+180.4 equation:

200=-16t^2+80t+180.4

We move all terms to the left:

200-(-16t^2+80t+180.4)=0

We get rid of parentheses

16t^2-80t-180.4+200=0

We add all the numbers together, and all the variables

16t^2-80t+19.6=0

a = 16; b = -80; c = +19.6;
Δ = b2-4ac
Δ = -802-4·16·19.6
Δ = 5145.6
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-80)-\sqrt{5145.6}}{2*16}=\frac{80-\sqrt{5145.6}}{32}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-80)+\sqrt{5145.6}}{2*16}=\frac{80+\sqrt{5145.6}}{32}
$