880=-16t^2+256t

Solution for 880=-16t^2+256t equation:

880=-16t^2+256t

We move all terms to the left:

880-(-16t^2+256t)=0

We get rid of parentheses

16t^2-256t+880=0

a = 16; b = -256; c = +880;
Δ = b2-4ac
Δ = -2562-4·16·880
Δ = 9216
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9216}=96$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-256)-96}{2*16}=\frac{160}{32}
=5
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-256)+96}{2*16}=\frac{352}{32}
=11
$