1) 50/10 = 5 km per hour, so the boat travels 7*5 = 35 km in 7 hrs. So, the answer is 35, D.
2) I can't actually show the work, but the points are the same in graph as in the table, so the answer is D.
3) If you look closely, you will realize that it's just the multiplication table of 6, so the answer is obviously C.
Hope this helps!