Sorry it's an exam. I wish that I could.
I sad I could not help you :(
If you wanted the time progressed, it's 7 hours and 30 minutes
Answer:
4.5
Step-by-step explanation:
when the height is 0 the ball will hit the ground
so the equation is
-12t²+54t=0
12t²-54t=0
2t²-9t=0
t(2t-9)=0
t=0
t=4.5
so the answer is
4.5
This is how i would do it divide 81 by 2 then take 21 of one side and add it to the other side
