What's the answer to these math problems? how did you solve it?

What are the coordinates of the point is 1/4 of the way from a (-6, -3) to b (6, 1)? a. (-3, -2) b. (0, -2) c. (-1, 0) d. (3, 2)

Gravel is being dumped from a conveyor belt at a rate of 25 ft3/min, and its coarseness is such that it forms a pile in the shape of a cone whose base diameter and height are always equal. how fast is the height of the pile increasing when the pile is 14 ft high? (round your answer to two decimal places.) ft/min

How many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.) how many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.)