25=-16t^2+60t

Solution for 25=-16t^2+60t equation:

25=-16t^2+60t

We move all terms to the left:

25-(-16t^2+60t)=0

We get rid of parentheses

16t^2-60t+25=0

a = 16; b = -60; c = +25;
Δ = b2-4ac
Δ = -602-4·16·25
Δ = 2000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{2000}=\sqrt{400*5}=\sqrt{400}*\sqrt{5}=20\sqrt{5}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-60)-20\sqrt{5}}{2*16}=\frac{60-20\sqrt{5}}{32}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-60)+20\sqrt{5}}{2*16}=\frac{60+20\sqrt{5}}{32}
$