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Ginny and Jenna are 20 miles from home. They have one pair of roller skates. Jenna walks 4mph and skates 9mph. Ginny walks 3 mph and skates 8mph. They start for home at the same time.

First, Ginny has the skates and Jenna walks. Ginny skates for a while, then takes the roller skates off and starts walking.When Jenna reaches the roller blades, she puts them on and starts skating home.

If they both start at 4:00 and arrive home at the same time, what time is it when they get home?

 Jun 21, 2021

Best Answer 

 #1
avatar+33360 
+2

Jenna walks the distance Ginny skates      x = jenna walk distance = ginny skate distance

Ginny walks the distance Jenna skates      y = ginny walk distance = jenna skate distance

 

 

distance = rate * time

 

  jenna      x/4 + y/9   is total time

  ginny      x/8 + y/3   is total time

                        the total times are the same           and the distance   x+ y =20     or    y = 20 - x

 

   x/4 + (20-x)/9  = x/8 + (20-x)/3

  x/8 = 2(20-x)/9 

  x/8 = (40-2x)/9

9/8 x = 40 -2x

25/8x = 40 

x = 12.8     y = 7.2  miles

 

Jenna walks 12.8 miles @ 4m/h    and skates 7.2 miles  @ 9 m/h =   4 hours total 

Ginny skates 12.8 miles @ 8 m/h   and  walks 7.2 m at 3 m/h =  4 hr                              If they start at 4 ...they arrive at 8:00

 Jun 22, 2021
 #1
avatar+33360 
+2
Best Answer

Jenna walks the distance Ginny skates      x = jenna walk distance = ginny skate distance

Ginny walks the distance Jenna skates      y = ginny walk distance = jenna skate distance

 

 

distance = rate * time

 

  jenna      x/4 + y/9   is total time

  ginny      x/8 + y/3   is total time

                        the total times are the same           and the distance   x+ y =20     or    y = 20 - x

 

   x/4 + (20-x)/9  = x/8 + (20-x)/3

  x/8 = 2(20-x)/9 

  x/8 = (40-2x)/9

9/8 x = 40 -2x

25/8x = 40 

x = 12.8     y = 7.2  miles

 

Jenna walks 12.8 miles @ 4m/h    and skates 7.2 miles  @ 9 m/h =   4 hours total 

Ginny skates 12.8 miles @ 8 m/h   and  walks 7.2 m at 3 m/h =  4 hr                              If they start at 4 ...they arrive at 8:00

ElectricPavlov Jun 22, 2021

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