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?
+36916 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
+36916 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
