Hey. Good afternoon.
120$ --- 80%
x --- 100%
80x = 12000
x = 12000/80
x = 150$
Sorry my bad english, i'm Brazilian.
Plug in f(t) = 0. We do this because f(t) represents the height and a height of 0 means you're at the ground.
f(t) =-5t^2 + 20t + 60
0 = -5t^2 + 20t + 60
-5t^2 + 20t + 60 = 0
Now solve for t using the quadratic formula
Answer:
D
Step-by-step explanation: