Question

PLZ help picture included

Answer 1

4 miles

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

`s=(d)/(t)`

The distance is equal to multiply the speed by the time

`d=st`

we know that

`18\ min=(18)/(60)\ hours`

The distance to his friend's house and the distance of return is the same

so

`10x=4(x+(18)/(60))`

solve for x

`10x=4x+(18)/(15)`

subtract 4x both sides

`10x-4x=(18)/(15)`

`6x=(18)/(15)`

`x=(1)/(5)\ hours`

The total distance of the round trip is

`y=10x+4x+(18)/(15)`

substitute the value of x

`y=10((1)/(5))+4((1)/(5))+(18)/(15)`

`y=2+2=4\ miles`