Answer:
9.099 seconds
Step-by-step explanation:
The rock hits the surface of the moon when is t is 0.
[tex]-t^2 + 8t + 10 = 0\\t^2 - 8t - 10 = 0[/tex]
Use the quadratic formula
t = -1.099 and 9.099
Since time can't be negative, the answer is t = 9.099