A parachutist descends 90 feet In 5 seconds express the rate of the parachutist change in height as a unit rate

Hi my sisters and brothers can tell me the answer because i don’t understand the question

Given a: b and b: c, find a: b: c. write the ratio in simplest form. a: b=6: 10 and b: c=21: 33

80 points suppose marcy made 45 posts online. if 23 of them contained an image, what percent of her posts had images? round your answer to the nearest whole percent. 54 percent 51 percent 49 percent 48 percent