Answer:
4 miles
Step-by-step explanation:
Walking:
Distance = d miles
Rate = 4 mph
Time = t hours
[tex]d=4\cdot t[/tex]
Biking:
Distance = d miles
Rate = 10 mph
Time [tex]=t-\dfrac{18}{60}=t-0.3[/tex] hours (convert minutes to hours)
[tex]d=10\cdot (t-0.3)[/tex]
Hence,
[tex]4t=10(t-0.3)\\ \\4t=10t-3\\ \\4t-10t=-3\\ \\-6t =-3\\ \\6t=3\\ \\t=\dfrac{3}{6}=\dfrac{1}{2}=0.5\ hour[/tex]
Therefore, the distance to friend's house is
[tex]d=4\cdot 0.5=2\ miles[/tex]
and the total distance of the round trip is
[tex]2+2=4\ miles[/tex]
