Integration. Please help ASAP

Molly shared a spool of ribbon with 12 people. each person received 3 feet of ribbon. which equation can she use to find r, the number of feet of ribbon that her spool originally had?

Mr. vector door is buying two new cowboy hats all together the hats cost $75.12 the second heart cost twice as much as the first hat what is the price of the more expensive at round to the nearest hundredth

Aweekly newspaper charges $72 for each inch in length and one column width. what is the cost of an ad that runs 2 column inches long and 2 columns wide? its not 288