It appears you are on the right track.
answer is D i just took the test and i got it right
Answer:
The rate of the boat in still water is 40 miles per hour
The rate of the current is 10 miles per hour
Step-by-step explanation:
we know that
The speed or rate is equal to divide the distance by the time
Let
x ----> the rate of the current (miles per hour)
y ----> the rate of the boat in still water (miles per hour)
we have that
<em>going upstream </em>
----> equation A
<em>going downstream </em>
----> equation B
Solve the system of equations by elimination
Adds equation A and equation B
<em>Find the value of x </em>
therefore
The rate of the boat in still water is 40 miles per hour
The rate of the current is 10 miles per hour
Answer:

Step-by-step explanation:

Rule of exponents
, 
=> 
=> 
Combining same bases
=> 
When bases are same , powers are to be added
=> 
=> 
=> 
=> 
=> 9