Is someone nice enough and answer and explain this to me ?

The volume of a box varies directly with its length if a box in the group has a length of 30inches and k=24 what is its volume

Use mathematical induction to prove the statement is true for all positive integers n, or show why it is false. 1^2 + 4^2 + 7^2 + + (3n - 2)^2 = [n(6n^2-3n-1)/2]

What is the midpoint of np if n (1,9) and p (-5-1)