100=-16t^2+55t+325

Solution for 100=-16t^2+55t+325 equation:

100=-16t^2+55t+325

We move all terms to the left:

100-(-16t^2+55t+325)=0

We get rid of parentheses

16t^2-55t-325+100=0

We add all the numbers together, and all the variables

16t^2-55t-225=0

a = 16; b = -55; c = -225;
Δ = b2-4ac
Δ = -552-4·16·(-225)
Δ = 17425
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:

$\sqrt{\Delta}=\sqrt{17425}=\sqrt{25*697}=\sqrt{25}*\sqrt{697}=5\sqrt{697}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-55)-5\sqrt{697}}{2*16}=\frac{55-5\sqrt{697}}{32}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-55)+5\sqrt{697}}{2*16}=\frac{55+5\sqrt{697}}{32}
$