Sally's teacher created a math problem, but she colored the marbles with invisible ink! Please help by determining how many marbles in the bag were blue if the outcome of the probability of landing on green and choosing a blue marble is 5/21?

Mozart lenses inc. recently introduced seelites, a thinner lens for eyelasses. of a sample of 800 eyeglass wearers, 246 said they would purchases their next pair of eyeglasses with the new lenses. lenses inc. estimates that the number of people who purchase eyeglasses in a year is 1,700,000. most eyeglasses wearer buy one new pair of eyeglasses a year. what is the annual sales potential for the new lenses.