It took John 12 hours riding his bike to make the round trip to his uncle's. If he averaged 20 mph out and 30 mph back, how long did he travel each way? (Round answer to nearest tenth.)

{Out______a0 hrs., back _______a1 hrs.}

Question

It took John 12 hours riding his bike to make the round trip to his uncle's. If he averaged 20 mph out and 30 mph back, how long did he travel each way? (Round answer to nearest tenth.)

{Out______a0 hrs., back _______a1 hrs.}

anonymous · Answer

anything guys

hero · Answer

Okay, sorry. So to set this up use d = rt

On the way there

Distance = d1
Rate = 20mph
time = t

On the way back:

Distance = d2
Rate = 30 mph
Time = 12 - t

d1 = 20t
d2 = 30(12 - t)

d1 = d2
20t = 30(12 - t)
20t = 360 - 30t
(20 + 30)t = 360
50t = 360
t = 360/50
  = 36/5
  = (35 + 1)/5
 = 7 + 1/5

hero · Answer

That's how many hours it took to get there. To get back do

12 - (7 + 1/5)

12 - 7 - 1/5
5 - 1/5

4 + 5/5 - 1/5
4 + 4/5 hrs to get back

hero · Answer

So 

7 + 1/5 hours to get there
4 + 4/5 hours to get back

hero · Answer

To be more exact we can covert the fractions to minutes
1/5 of an hour is 12 minutes
4/5 of an hour is 48 minutes so...

It took 

7 hours 12 minutes to get there
4 hours and 48 minutes to get back