SOLUTION: While training for a biatholon race, Kevin covered a total distance of 9 km by swimmmiing for 45 min and running for 20 min. The next day he swam for 30 min and ran for 40 min, co

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: While training for a biatholon race, Kevin covered a total distance of 9 km by swimmmiing for 45 min and running for 20 min. The next day he swam for 30 min and ran for 40 min, co      Log On

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Question 364791: While training for a biatholon race, Kevin covered a total distance of 9 km by swimmmiing for 45 min and running for 20 min. The next day he swam for 30 min and ran for 40 min, covering 14 km. Find his rates (in km/h) for swimming and running. (Assume these rates are constant.)
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let s = his rate swimming in km/hr
Let r = his rate running in km/hr
given:
(1) s%2A%283%2F4%29+%2B+r%2A%281%2F3%29+=+9 km
(2) s%2A%281%2F2%29+%2B+r%2A%282%2F3%29+=+14 km
Multiply both sides of (1) by 12
and both sides of (2) by 6
(1) 9s+%2B+4r+=+108
(2) 3s+%2B+4r+=+84
Subtract (2) from (1)
(1) 9s+%2B+4r+=+108
(2) -3s+-+4r+=+-84
6s+=+24
s+=+4
and
(2) 3%2A4+%2B+4r+=+84
4r+=+84+-+12
4r+=+72
r+=+18
He swims 4 km/hr and runs 18 km/hr