2500=-16t^2+400t+100

Solution for 2500=-16t^2+400t+100 equation:

2500=-16t^2+400t+100

We move all terms to the left:

2500-(-16t^2+400t+100)=0

We get rid of parentheses

16t^2-400t-100+2500=0

We add all the numbers together, and all the variables

16t^2-400t+2400=0

a = 16; b = -400; c = +2400;
Δ = b2-4ac
Δ = -4002-4·16·2400
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-400)-80}{2*16}=\frac{320}{32}
=10
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-400)+80}{2*16}=\frac{480}{32}
=15
$