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

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

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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) (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.
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