Question 263584
Meg traveled 7 miles yesterday walking for one half-hour and biking for one half-hour. Today traveling at the same rates she traveled a total of 6 miles by walking for 40 mintues and biking for 20 mintues. What was her walking and biking rates? The answer is walking 4mph and biking 10mph. 
Let walking rate be "w": let biking rate be "b":
Equations:
(1/2)w + (1/2)b = 7
(2/3)w + (1/3)b = 6
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Modify the equations:
 w  +  b  = 14
2w  +  b  = 18
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Subtract 1st from 2nd equation to get:
w  = 4 mph (walking rate)
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Since w + b = 14, w = 10 mph (walking rate)
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Cheers,
Stan H.