616=202t-4.9t^2

Solution for 616=202t-4.9t^2 equation:

616=202t-4.9t^2

We move all terms to the left:

616-(202t-4.9t^2)=0

We get rid of parentheses

4.9t^2-202t+616=0

a = 4.9; b = -202; c = +616;
Δ = b2-4ac
Δ = -2022-4·4.9·616
Δ = 28730.4
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{-(-202)-\sqrt{28730.4}}{2*4.9}=\frac{202-\sqrt{28730.4}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-202)+\sqrt{28730.4}}{2*4.9}=\frac{202+\sqrt{28730.4}}{9.8}
$