Question 1028108

Fred rode his bike up a mountain at 12 km/h and then back down at 48km/h. If he made the round trip in 1hr 20mins how far is it up the hill?
<pre>Let distance, one-way be D
Then time up-hill = {{{D/12}}}, and time downhill = {{{D/48}}}
We then get the following TIME equation: {{{D/12 + D/48 = 1&1/3}}}____{{{D/12 + D/48 = 4/3}}}
4D + D = 64 ------ Multiplying by LCD, 48 
5D = 64
D, or distance = {{{64/5}}}, or {{{highlight_green(matrix(1,2, 12.8, km))}}}