a cruise boat travels 84 miles downstream in 2 hours and ret

a cruise boat travels 84 miles downstream in 2 hours and returns upstream in 6 hours find the rate of the stream

Solution

Formula is D = r x t

Down stream = r + c
Upstream = r - c

Distance = 84 mile w/c is the same in both Up and Downstream

Time = Up 6 hrs
Time = Down 2 hrs

The equation is;

84 = (r + c)* 2 Downstream
84 = (r - c)* 6 Upstream

(84 = 2r + 2c)*-3 ( since you want to solve for the current, eliminate r
84 = 6r - 6c by multiplying -3)

-252 = -6r - 6c
84 = 6r - 6c

It yields -168 = -12 c devide both by -12 to get the value of c

c = 14 mph that\'s the speed of the stream