Final answer:
Charmaine lives 288 miles away from the mountains.
Step-by-step explanation:
To solve this problem, we can use the formula:
Distance = Rate x Time
Let's assume the distance Charmaine lives from the mountains is d miles.
On the way there, the trip took 9 hours and her average rate was r mph. This can be expressed as:
d = 9r
On the way back, the trip took 4 hours and her average rate was 40 mph faster than the rate on the way there, r+40. This can be expressed as:
d = 4(r + 40)
Now, we can solve the system of equations to find the distance Charmaine lives from the mountains:
9r = 4(r + 40)
Simplifying the equation, we get:
9r = 4r + 160
Subtracting 4r from both sides, we get:
5r = 160
Dividing both sides of the equation by 5, we get:
r = 32
Now, we can substitute the value of r into either equation to find the distance, d:
d = 9r
d = 9(32)
d = 288
Therefore, Charmaine lives 288 miles away from the mountains.