Question 288520
The basic equation we have to solve is d = rt, where d=distance, r=rate of speed, and t=time.
.
s = maximum speed of the boat in calm water
c = current speed
s+c = rate of speed going down stream
s-c = rate of speed going up stream
t = 7
.
Upstream...
d = 385
t = 7
r = d/t = 55
.
Downstream...
d = 623
t = 7
r = 89
.
s + c = 89
s - c = 55
2s = 144
s = 72
.
s - c = 55
72 -c = 55
c = 17
.
s = 72
c = 17
.
Done