Please help i only need the standard notation :(

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?

Taylor wants to paint his rectangular deck that is 41 feet long and 24 feet wide. a gallon of paint covers about 350 square feet. how many gallons of paint will taylor need to cover the entire deck? round your answers to two decimal places when necessary.

Abag contains 10 white golf balls and 6 striped golf balls. a golfer wants to add 112 golf balls to the bag. he wants the ratio of white to striped gold balls to remain the same. how many of each should he add?