60=-16t^2-64t+60

Solution for 60=-16t^2-64t+60 equation:

60=-16t^2-64t+60

We move all terms to the left:

60-(-16t^2-64t+60)=0

We get rid of parentheses

16t^2+64t-60+60=0

We add all the numbers together, and all the variables

16t^2+64t=0

a = 16; b = 64; c = 0;
Δ = b2-4ac
Δ = 642-4·16·0
Δ = 4096
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4096}=64$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(64)-64}{2*16}=\frac{-128}{32}
=-4
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(64)+64}{2*16}=\frac{0}{32}
=0
$