Question

a boat goes 30km upstream and 44km down stream in 10 hours. In 13 hours it can go 40km upstream and 55km downstream. Determine the speed of the stream and that of the boat in still water​

Answer 1

we know that upstream (x-y)

downstream (x+y)

ATQ

30/(x-y)+44/(x+y)= 10---- eq 1

40/(x-y)+55(x+y)= 13----eq2

let (x-y)= U

let (x+y)= V

30u+44v=10

40u+55v=13

by elimination

120u+1760v=400

120u+1650v=390

110v=10

v = 1/11

put v in eq

30u+44*1/11=10

30u=10-4

30u=6

u=1/5

Now

U = x-y= 5

V = X+Y=11

2y= 6

y= 3

x=8