Answers

2014-06-08T08:30:14+08:00
Let  V_{b} be velocity of bicycle
let  t_{b} be time traveled of bicycle

Given:
 V_{m} = V_{b}+15 kph
 t_{m} =  t_{b} -2 hrs
 d_{b} = d_{m} = 60 km

formula:

d=Velocity x time

time= \frac{distance}{Velocity}

Solution:
time for bicycle

 t_{b}= \frac{60}{ V_{b} }

use  t_{b} on  d_{m} = V_{m}  x  t_{m}

60km=( V_{b}+15)(  \frac{60}{ V_{b} }-2)

 V_{b} =15kph

use  V_{b} =15kph on  t_{b}= \frac{60}{ V_{b} }

 t_{b}= \frac{60}{15kph}

 t_{b} = 4 hrs

solve for  t_{m} :

 t_{m} = 4hrs -2 hrs

 t_{m} =2hrs

solve for  V_{m} :

 V_{m} = 15kph+15 kph

 V_{m} =30kph
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