a woman throws her keys straight up at 8.49 m/s. her friend catches them 2.89 m higher. how long were the keys in the air? (unit = s)

Alright this one is just kinematics, you can use one of the big four equations and in this case this one works because acceleration is constant and you don't have the final velocity to worry а bout:

Δx = displacement

Vi = initial velocity

T = time

A = acceleration

Δx = (Vi) (t) + (1/2) (a) (t^2)

A=9.8m/s2

Vi=8.49 m/s

Δx=2.89 meters

Then plug in:

2.89 = (8.49) (t) + (1/2) (9.8) (t^2)

Then solve for t and you're all set.