X+2x=9what does x equal? and how do i get the answer?

What is the exact volume of the cone? (height is 9 cm, the radius is 15 cm)

20 sharpened pencils are placed in a box containing an unknown number of unsharpened pencils suppose 15 pencils are removed at random and five of the remove pencils are sharpened based on this is it reasonable to assume that the number of unsharpened pencil is 40 explain your reasoning

The probability of drawing a heart from a standard deck of cards is .25. you record the card you draw and return the card before shuffling to ensure a binomial distribution. if you do this 20 times what is the probability that you will draw a heart 7 times? a. 0.888 b. 0.001 c. 0.112 d. 0.473