How fast was she paddling, and what was the speed of the current?

Question

Salina was paddling up and down the river over Labor Day weekend.  She travelled 3 miles downstream in 2 hours.  It took her twice that long to get back to her car.  How fast was she paddling, and what was the speed of the current?

Answer 1

distance=rate*time

d=rt

3=(r+c)2 where c=rate of the current

3=(r-c)4

(3/2)=(r+c)

(3/4)=(r-c)

add the equations

(3/2)+(3/4)=2r

(6/4)+(3/4)=2r

(9/4)=2r

(1/2)(9/4)=(1/2)(2)(r)

(9/8)=r

rate of paddling=9/8 or 1 1/8 mph

3=[(9/8)+c)]2

(3/2)=(9/8)+c

12/8=(9/8)+c

(12/8)-(9/8)=c

3/8=c

rate of current=3/8 mph