SOLUTION: Joe exercises 21 hours per week by walking and biking. He averages 3 MPH walking and 12 MPH biking. If he covers 180 miles per week, how far does he walk each week? How far does he

Algebra ->  Customizable Word Problem Solvers  -> Coins -> SOLUTION: Joe exercises 21 hours per week by walking and biking. He averages 3 MPH walking and 12 MPH biking. If he covers 180 miles per week, how far does he walk each week? How far does he      Log On

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Question 994974: Joe exercises 21 hours per week by walking and biking. He averages 3 MPH walking and 12 MPH biking. If he covers 180 miles per week, how far does he walk each week? How far does he bike?
Answer by CubeyThePenguin(3113) About Me  (Show Source):
You can put this solution on YOUR website!
w = hours walked
b = hours biked

3w + 12b = 180
w + b = 21

Multiply the second equation by 3.

3w + 12b = 180
-(3w + 3b = 63)
--------------------
9b = 117
b = 13

Joe biked 13 * 12 = 156 miles.