-16.1=10t-4.9t^2

Solution for -16.1=10t-4.9t^2 equation:

-16.1=10t-4.9t^2

We move all terms to the left:

-16.1-(10t-4.9t^2)=0

We get rid of parentheses

4.9t^2-10t-16.1=0

a = 4.9; b = -10; c = -16.1;
Δ = b2-4ac
Δ = -102-4·4.9·(-16.1)
Δ = 415.56
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{-(-10)-\sqrt{415.56}}{2*4.9}=\frac{10-\sqrt{415.56}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+\sqrt{415.56}}{2*4.9}=\frac{10+\sqrt{415.56}}{9.8}
$