What do they mean by what is a rule for the sequence below on the pic

There were 816 people at a concert when a band started to play. after each song, only half the people stayed to hear the next song. how many people were left at the concert after x songs? write a function to represent this scenario.

Pat listed all the numbers that have 15 as a multiple write the numbers in pats list

If you have the following equation, 2/3x+5/6-x=2-3/4x what would you multiply each term by to get rid of all the fractions