How do I solve for:

5000 = 45t^2 + 240t + 450

45t^2 + 240t - 4550 = 0

9t^2 + 48t - 910 = 0
by the formula
t = (-48 ± √35064)/18 = (-48 ± 2√8766)/18
= (-24 ± √8766)/9

Use your calculator if you want a decimal answer