0=-16t^2+85t+4

Solution for 0=-16t^2+85t+4 equation:

0=-16t^2+85t+4

We move all terms to the left:

0-(-16t^2+85t+4)=0

We add all the numbers together, and all the variables

-(-16t^2+85t+4)=0

We get rid of parentheses

16t^2-85t-4=0

a = 16; b = -85; c = -4;
Δ = b2-4ac
Δ = -852-4·16·(-4)
Δ = 7481
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{-(-85)-\sqrt{7481}}{2*16}=\frac{85-\sqrt{7481}}{32}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-85)+\sqrt{7481}}{2*16}=\frac{85+\sqrt{7481}}{32}
$