Answer: -6p - 78
Step-by-step explanation:
-5 (3p + 3) + 9(-7 + p)
-15p -15 - 63 + 9p
-6p-78
Once the rock hits the ground, we know that its height will be equal to 0m
because of this, we can replace H(x) with 0

now all we have to do is get x by itself
so..

then


now take the square root of each side

2.857 seconds (rounded to the third decimal)
Answer: C
Step-by-step explanation: