Can someone plz help me solved this problem! I’m giving you 10 points! I need help plz help me! Will mark you as brainiest!

time = 20 seconds

Step-by-step explanation:

h(t) = -16t² + 316t + 80

The shape of this graph is an upside parabola ∩.  

It lands on the ground when height (h) = 0

Set the equation equal to zero, factor, and solve for t.

0 =  -16t² + 316t + 80

0 =  4t² - 79t - 20              divided both sides by -4

0 = (4t + 1)(t - 20)               factored the equation

t = -1/4      t = 20              Applied Zero Product Property and solved for t

Since we know time cannot be negative, disregard t = -1/4

The only valid solution is: t = 20

sin3a=12/15

step-by-step explanation:

since one side was multiplied by 3 the other side must also be multiplied by 3.