Please help LOL I don’t understand number 8 by the way

Three cylinders have a volume of 2836 cm^3. cylinder a has a height of 900 cm. cylinder b has a height of 225 cm. cylinder c has a height of 100 cm. find the radius of each cylinder. use 3.14 as an approximate for π

Isuck at math ; ^; m a student solved this problem and said the answer is 3 feet. chase had a roll of ribbon that contained 7 7/8  feet of ribbon. he cut off one piece that was 3 5/8  feet long and another piece that was 1 1/4  feet from the roll. how much ribbon was left on the roll? is the student's answer reasonable? yes, the answer is reasonable. no, the answer is not reasonable. it should be about 2 feet. no, the answer is not reasonable. it should be about 13 feet. no, the answer is not reasonable. it should be about 4 feet.

Ke’ajah has a coupon for 1/3 off the regular price, t, of a tent. which expression represents the price of the tent using the coupon? select the two correct expressions. a. 1/3t b. 2/3t c. t - 1/3 d. t - 2/3 e. t - 1/3t f. t - 2/3t