rate=distance/time

Question

in a walkathon to raise money for a 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 2 h and 15 min. How many miles long was the walkathon?

Answer 1

 x = her walking distance

2x= her jogging dist

 

2 hr 15 min = 2.25 hrs

Time = dist/speed

 

Walk time + jog time = total time

x/5          +  2x/8    = 2.25

Multiply by 40, results:
8x + 5(2x) = 40(2.25)
8x + 10x= 90
18x = 90
x= 5
x = 5 mi, walking
then

2x=10 mi, jogging

 

so toatal distance =5+10=15 miles