How do I solve this?

Question

The equation d = 1/2at² gives the distance d in ft that an object travels from rest while accelerating, where a is the acceleration and t is the time.

a. How far has an object traveled in 4s when the acceleration is 5ft/s²?

b. How long does it take an object to travel 100ft when the acceleration is 8ft/s²?

Answer 1

td = (0.5)at²

a. d = (0.5)(5)(4²)

b. 100 = (0.5)(8)t²

 

Can you solve and answer?