Answer:
The rate in still water is 13.5 miles per hour and the rate of the current is 4.5 miles per hour.
Step-by-step explanation:
The velocity of an object is equal to the displacement divided by the time:
Going with the current the velocity in miles per hour is:
Going against the current, 3/4 of 72 miles is 54 miles, then the velocity in miles per hour is:
The velocity of going with the current is the sum of the rate of being still() and the rate of the current(). And the velocity of going against is the difference between the two rates so:
Adding the equation to solve for :
Substituting in one equation to find :
The rate in still water is 13.5 miles per hour and the rate of the current is 4.5 miles per hour.