15=-16t^2+3t+15

Solution for 15=-16t^2+3t+15 equation:

15=-16t^2+3t+15

We move all terms to the left:

15-(-16t^2+3t+15)=0

We get rid of parentheses

16t^2-3t-15+15=0

We add all the numbers together, and all the variables

16t^2-3t=0

a = 16; b = -3; c = 0;
Δ = b2-4ac
Δ = -32-4·16·0
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-3}{2*16}=\frac{0}{32}
=0
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+3}{2*16}=\frac{6}{32}
=3/16
$