-32=75t-4.90t^2

Solution for -32=75t-4.90t^2 equation:

-32=75t-4.90t^2

We move all terms to the left:

-32-(75t-4.90t^2)=0

We get rid of parentheses

4.90t^2-75t-32=0

a = 4.90; b = -75; c = -32;
Δ = b2-4ac
Δ = -752-4·4.90·(-32)
Δ = 6252.2
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{-(-75)-\sqrt{6252.2}}{2*4.90}=\frac{75-\sqrt{6252.2}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-75)+\sqrt{6252.2}}{2*4.90}=\frac{75+\sqrt{6252.2}}{9.8}
$