Help please !! don't get this one :/

Which of the fallowing best completes the sequence 5,10,15, a) 30 b) 22 c)25 d)35

Acylinder with a base diameter of x units has a volume of jxcubic units which statements about the cylinder are true? check all that apply. the radius of the cylinder is 2 x units. the radius of the cylinder is 2x units. the area of the cylinder's base is 200 square units. the area of the cylinder's base is a square units. the height of the cylinder is 2x units. the height of the cylinder is 4x units. mark this and return save and exit next submit

Is the power produced directly proportional to the wind speed, give reasons for your answer?