Answer:
18432 km/h
Step-by-step explanation:
It is given that a sound wave travels through iron at a rate of 5120 m/s.
We know that
1 km = 1000 m
1 hour = 60 minutes
1 minutes = 60 second
Using these conversions we get
1 m = 0.001 km
1 hour = 3600 second


Therefore, the sound wave travels through iron at a rate of 18432 km/h.
84-48=36
36/3=12
The tree grows 12 inches every year
The answer is A. I plugged it into a TI-83 calculator. If you need to know how I did that I will be happy to help