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

Answer:
16
Step-by-step explanation:
-4(16+5)
5+16=20
20 sub -4 = 16
The answer is a and c
Hope this helps.
Answer:
One
Step-by-step explanation:
<em>Testing only one variable at a time lets you analyze the results of your experiment to see how much a single change affected the result. If you're testing two variables at a time, you won't be able to tell which variable was responsible for the result.</em>
<em>Hope this helps,</em>
<em>:)</em>
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Answer:
2.93
Step-by-step explanation: