Answer:
4 miles
Step-by-step explanation:
Let
x ----> the time to returned back biking in hours
d ---> the distance in miles
s ---> speed in miles per hour
Remember that
The speed or rate is equal to divide the distance by the time
The distance is equal to multiply the speed by the time
we know that
The distance to his friend's house and the distance of return is the same
so
solve for x
subtract 4x both sides
The total distance of the round trip is
substitute the value of x