Lisa rowed her boat for two miles downstream. The trip took her 20 minutes. She then turned around and rowed back
the two miles. It took her one hour to row back upstream.
a. At what rate of speed did Lisa row downstream?
b. At what rate of speed did Lisa row upstream?
c.
Suppose Lisa’s speed rowing upstream was 4 miles per hour. How long would it have
taken her to travel two miles?
v = rowing speed
u = current speed
2 miles = (v+u)(20/60)
2 miles = (v-u) (1)
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then
2 = v/3 + u/3
2/3 = v/3 - u/3
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4/3 = 2 u/3
u = 2 etc