Bryce's speedboat can travel 58 miles upstream against a 3-mph current in the same amount of time it travels 70 miles downstream with a 3-mph current. Find the speed of Bryce's boat.
REmember that
the speed is equal to divide the distance by the time
s=d/t
we have that
Upstream
speed is equal to
(58/t)-3
Downstream
the speed is equal to
(70/t)+3
Let
s -----> speed of Bryce's boat
Remmeber that the time in both cases
so
t=d/s
Upstream
time is equal to
58/(s-3)------> equation 1
Downstream
time is equal to
70/(s+3) ------> equation 2
Equate both equations
58/(s-3)=70/(s+3)
solve for s
multiply in cross
58(s+3)=70(s-3)
58s+174=70s-210
70s-58s=174+210
12s=384
s=32 mph
answer is 32 mph