Answer:
0.6 miles
Explanation:
Let's say the store is x miles away, she walks to the store in a hours, and she walks back in b hours.
First, her total time = time walked there + time walked back = a + b = 15 minutes = 1/4 of an hour = 0.25 hours
a + b = 0.25 (because a and b are in hours)
distance = speed * time
x = 6 miles/hour * a hours = 6a miles
x = 4 miles/hour * b hours = 4b miles
If we can find a or b, we can find x.
4b = x = 6a
4b = 6a
a + b = 0.25
We now have two equations with two variables. Using substitution, we can solve for one of them
a + b = 0.25
subtract a from both sides to find b
0.25 - a = b
plug that into the other equation, 4b = 6a
4(0.25-a) = 6a
1 - 4a = 6a
add 4a to both sides to isolate a and its coefficient
1 = 10a
divide both sides by 10 to solve for s
a = 1/10 of an hour = 0.1 of an hour = 60 minutes / 10 = 6 minutes
6a = x
6(0.1) = x
0.6 = x
the store is 0.6 miles away