Question 1110188
let speed of boat in still water be x km/h
y the speed of current 
x+y = speed with current
x-y = speed against current

time upstream + time down stream = total time
 
condition I
30/(x-y)  + 44/(x+y) = 10
condition II
40/(x-y) + 55/(x+y) = 13

Let 1/(x+y) = a and 1/(x-y) =b

plugging a and b

30b+ 44a = 10
40b + 55a=13

solving the above we get 
a= 1/11 and b = 1/5

1/(x+y) = 1/11
1/(x-y) = 1/5
Therefore x+y = 11
          x-y = 5

Solve x=8 and y=3  speed in km/h