SOLUTION: a helicopter travels 630 kms. at the same time that a car travels 210 kms. If the helicopter travels 60 km. per hour faster than the car, how fast does each of them travel?

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: a helicopter travels 630 kms. at the same time that a car travels 210 kms. If the helicopter travels 60 km. per hour faster than the car, how fast does each of them travel?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 162271: a helicopter travels 630 kms. at the same time that a car travels 210 kms. If the helicopter travels 60 km. per hour faster than the car, how fast does each of them travel?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
d+=+r%2At for both and
t is the same for both
r%5Bh%5D+=+r%5Bc%5D+%2B+60
For helicopter:
630+=+r%5Bh%5D%2At
630+=+%28r%5Bc%5D+%2B+60%29%2At
For car:
210+=+r%5Bc%5D%2At
------------------
For helicopter:
t+=+630+%2F+%28r%5Bc%5D+%2B+60%29
For car:
t+=+210+%2F+r%5Bc%5D
The time,t is the same for both, so
630+%2F+%28r%5Bc%5D+%2B+60%29+=+210+%2F+r%5Bc%5D
Multiply both sides by r%5Bc%5D%2A%28r%5Bc%5D+%2B+60%29
630r%5Bc%5D+=+210%2A%28r%5Bc%5D+%2B+60%29
630r%5Bc%5D+=+210r%5Bc%5D+%2B+12600
420r%5Bc%5D+=+12600
r%5Bc%5D+=+30 km/hr
and, since
r%5Bh%5D+=+r%5Bc%5D+%2B+60
r%5Bh%5D+=+90 km/hr
The car travels 30 km/hr and the helicopter
trvels 90 km/hr
check:
630+%2F+%28r%5Bc%5D+%2B+60%29+=+210+%2F+r%5Bc%5D
630+%2F+%2830+%2B+60%29+=+210+%2F+30
63%2F9+=+21%2F3
7+=+7
OK