Answer:
Speed of boat in still water is 6km/h
Speed of current is 4km/h
Step-by-step explanation:
We know speed = distance / time
Let the speed of boat in still water be x
Let the speed of current be y
Hence the speed of boat, down stream = 
Distance downstream = 20km
Time taken = 2 hours
We have

......(1)
Speed of boat upstream = 
Distance upstream = 4
Time taken = 2
We have

...(2)
Adding (1) & (2)


Substituting in (1) we get

488cm² is your answer
Step-by-step explanation:
the area of the composite figure=area of rectangle +area of triangle
=l×b+1/2 b×h=17×22+1/2×{22-10}×19 =488cm²
Answer:
2x and 7y, because they have different variables.
Step-by-step explanation:
That is 6 * sqrt(2*8*3*6)
= 6 sqrt 16 * sqrt 18
= 6 *4 * sqrt 9 * sqrt2
= 6*4*3 sqrt2
= 72 sqrt 2