Arthur D. answered 09/09/14
Tutor
4.9
(306)
Forty Year Educator: Classroom, Summer School, Substitute, Tutor
distance=rate*time
d=rt
r+10=rate riding his bike
r=rate walking
10 minutes=10/60 hours
15 minutes=15/60 hours
distance=rate*time(riding)+rate*time(walking)
2.75=(r+10)(10/60)+(r)(15/60)
2.75=(r+10)(1/6)+(r)(1/4)
multiply both sides by 12
33=(r+10)2+(r)3
33=2r+20+3r
33=5r+20
13=5r
r=13/5=2.6 km per hour (walking)
d=rt
d=2.6*(15/60)
d=2.6*(1/4)
d=0.65 km to the gym from the friend's house
d=12.6(10/60)
d=12.6(1/6)
d=2.1 km to the friend's house
2.1+0.65=2.75 km total distance as stated in the problem