1536=-16t^2+240t+4000

Solution for 1536=-16t^2+240t+4000 equation:

1536=-16t^2+240t+4000

We move all terms to the left:

1536-(-16t^2+240t+4000)=0

We get rid of parentheses

16t^2-240t-4000+1536=0

We add all the numbers together, and all the variables

16t^2-240t-2464=0

a = 16; b = -240; c = -2464;
Δ = b2-4ac
Δ = -2402-4·16·(-2464)
Δ = 215296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{215296}=464$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-240)-464}{2*16}=\frac{-224}{32}
=-7
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-240)+464}{2*16}=\frac{704}{32}
=22
$