I'd personally go with A and C, The rest don't make too much sense. Don't count on my answer just yet though.
Answer:
Speed of the river =
km per hour
Step-by-step explanation:
Speed of the boat in still water = 4 km per hour
Let the speed of the river = v km per hour
Speed of the boat upstream = (4 - v) km per hour
Time taken to cover 6 km = 
=
hours
Speed of the boat downstream = (4 + v) km per hour
Time taken to cover 12 km =
hours
Since, time taken by the boat in both the cases is same,

6(4 + v) = 12(4 - v)
24 + 6v = 48 - 12v
12v + 6v = 48 - 24
18v = 24
v = 
v =
km per hour
Because if you ask one student from each class you are getting a more accurate representation of the classes. If you were to ask one group you'd only get their opinion
Answer:
x+22 = 90
Step-by-step explanation:
The two angles are complementary, which means they add up to 90 degrees
x+22 = 90
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