Question 818496
Peter cycles to visit his grandma and then returns home by the same route.
 He always cycles at 4 km/h when going uphill, 12 km/h when going downhill and 6km/h when on level ground.
If his total cycling time is 2hours and 20 minutes, what is the total distance he cycles in km?
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Let x = dist up-hill or downhill
Let d = the one-way distance
then
(d-x) = dist on level ground
:
Write a time equation: time = dist/speed
to grandma + return home = 2{{{1/3}}} hrs
{{{x/4}}} + {{{((d-x))/6}}} + {{{((d-x))/6}}} + {{{x/12}}} = {{{7/3}}}
multiply by 12, cancel the denominators
3x + 2(d-x) + 2(d-x) + x = 4(7)
3x + 2d - 2x + 2d - 2x + x = 28
Combine like terms
3x - 2x - 2x + x + 2d + 2d = 28
4d = 28
d = 7 km one-way
2(7) = 14 km is the total distance
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