In 8 hrs C walks 3 Km more than D does in 6 hrs and in 7 hrs D walks 9 Km more than C does in 6 hrs;  how many kilometere does each walk in an hour?

Asked by Asfaque | 8th May, 2016, 10:53: PM

Expert Answer:

Let space space straight C space walks space straight x space km space in space 1 space hour space and space straight D space walks space straight y space km space in space 1 space hour

In space 8 space hrs space straight C space walks space 3 space Km space more space than space straight D space does space in space 6 space hrs
8 straight x space minus space 6 straight y space equals space 3......................... left parenthesis straight i right parenthesis

space In space 7 space hrs space straight D space walks space 9 space Km space more space than space straight C space does space in space 6 space hrs
7 straight y space minus space 6 straight x space equals space 9......................... left parenthesis ii right parenthesis

Adding space eq space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis space we space get space
2 straight x space plus space straight y space equals space 12
straight y space equals space 12 space minus space 2 straight x................. left parenthesis iiii right parenthesis

Substitute space left parenthesis iii right parenthesis space in space left parenthesis straight i right parenthesis space we space get

8 straight x space minus 6 left parenthesis 12 space minus space 2 straight x right parenthesis space equals space 3
8 straight x space minus 72 space plus 12 space straight x space equals space 3
20 straight x space equals space 75
straight x space equals 15 over 4.............. left parenthesis iv right parenthesis

Substitute space left parenthesis iv right parenthesis space in space left parenthesis iii right parenthesis space we space get
straight y space equals space 12 space minus space 2 open parentheses 15 over 4 close parentheses
straight y space equals 12 minus 15 over 2
straight y space equals space 9 over 2

Hence comma space straight C space walks space 15 over 4 space km space in space space one space hour space and space space straight D space walks space 9 over 2 space km space in space one space hour.

Answered by Vijaykumar Wani | 9th May, 2016, 11:11: AM