Find the sum of 1st 20 terms of an AP in which third term is 7and 7th term is 2more than thrice of its 3rd term

Diana is painting statues she has 7/8 of a liter of paint each statue requires 1/20 of a liter of paint how many statues can she paint?

Due to a packaging error, 4 cans labeled diet soda were accidentally filled with regular soda and placed in a 12 pack carton of diet soda. two cans were randomly selected from this 12 pack. what is the probability that both cans were regular soda?

There are 8 movies that you would like to see currently showing in theatres. in how many different ways can you choose a movie to see this saturday and one to see this sunday?