Can someone actually help me

What is the volume of a rectangular prism if the length is 10.4 mm the width is 5 mm in the height is 8 mm

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).

Mr. thompson is on a diet. he currently weighs 260 pounds. he loses 4 pounds per month. what part of the story makes the relationship not proportional?