Question 803394
x speed of boat in still water
y speed of current
down river speed = x+y

upstream speed = x-y

Distance = same upstream and downstream

d=rt

3(x+y)=5(x-y)

3x+3y=5x-5y

2x=8y
x=4y

distance = 3(x+y)

but x=4y
distance = 3(4y+y)
=15y

speed in still water = 4y

time = d/r

=15y/4y
=3.75 hours

Time in still water = 3.75 hours