SOLUTION: A man walked for 3 hours at 4.5 km/h and cycled for some time at 15km/h. Altogether, he traveled 21km. find the time taken for cycling? can anyone help me

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Question 1087331: A man walked for 3 hours at 4.5 km/h and cycled for some time at 15km/h. Altogether, he traveled 21km. find the time taken for cycling?
can anyone help me
Found 2 solutions by ikleyn, josgarithmetic:
Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
.
This time is equal to  %2821-3%2A4.5%29%2F15 = 0.5  of an hour.


Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
              SPEED        TIME       DISTANCE

WALK           4.5          3         4.5*3=13.5

CYCLE          15         7.5/15     21-13.5=7.5

Total                                   21

You're looking for 7.5%2F15=0.5, HALF an hour.