A painting is on sale at 50% off. The sale price is $320. What was the original price? I understand that you can do 320 x 2, however, my teacher will not accept that. How do I do it with a two-step equation?

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.