SOLUTION: In a walkathon to raise money for charity, Elisa walked a certain distance at 5 mi/h and then jogged twice that distance at 8 mi/h. Her total time walking and jogging was 2hr and 1

Question 155510: In a walkathon to raise money for charity, Elisa walked a certain distance at 5 mi/h and then jogged twice that distance at 8 mi/h. Her total time walking and jogging was 2hr and 15min. How many miles long was the walkathon? The answer is 15mi but I cannot formulate the equation.
Found 2 solutions by scott8148, Adam:
Answer by scott8148(6628) (Show Source): You can put this solution on YOUR website!
r*t=d __ so t=d/r __ 2hr15min is 9/4 hr

"Elisa walked a certain distance at 5 mi/h" __ Tw=d/5

"jogged twice that distance at 8 mi/h" __ Tj=2d/8=d/4

the total time is Tw+Tj __ the total distance is 3d

d/5+d/4=9/4 __ multiplying by 20 __ 4d+5d=45 __ 9d=45 __ d=5 __ 3d=15
Answer by Adam(64) (Show Source): You can put this solution on YOUR website!
There is an important equation of motion v-velocity, s-distance, t-time. We will use this to solve our problem. First we know the time 2 hours and 15 minutes that is 2.25 hours. We isolate t in the equation and get , we know two distances a and 2a (twice longer) and two velocities 5 and 8 mi/h and we can formulate
Cheers,
Adam
p.s. don't forget that a is not a complete distance ;)
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