Question 1065118
A grain barge travels on a river from point A to point B loading and unloading grain.
 The barge travels at a rate of 6 mph relative to the water.
 The river flows downstream at a rate of 1 mph.
 If the trip upstream takes 2 hours longer than the trip downstream, how far is it from point A to point B?
:
6+1 = 7mph is the downstream rate
6-1 = 5mph is the upstream rate
:
let d = the one way distance, A to B and B to A
Write a time equation; time = dist/speed
upstr time - downstr time = 2 hrs
{{{d/5}}} - {{{d/7}}} = 2 
clear fractions, multiply equation by 35, cancel the denominators
7d - 5d = 35(2)
2d = 70
d = 70/2
d = 35 mi is the dist from A to B
:
:
Check this by finding the actual time each way
35/5 = 7 hrs
35/7 = 5 hrs
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dif: 2 hrs