Nine more than half of a number is 21

Which expression is equivalent to sq-80

[15 points]find the quotient with the restrictions. (x^2 - 2x - 3) (x^2 + 4x + 3) ÷ (x^2 + 2x - 8) (x^2 + 6x + 8)

The two cylinders are similar. if the ratio of their surface areas is 9/1.44 find the volume of each cylinder. round your answer to the nearest hundredth. a. small cylinder: 152.00 m3 large cylinder: 950.02 m3 b. small cylinder: 972.14 m3 large cylinder: 12,924.24 m3 c. small cylinder: 851.22 m3 large cylinder: 13,300.25 m3 d. small cylinder: 682.95 m3 large cylinder: 13,539.68 m3