Coach South and Mr. Dr. Coach Rhodes are having a problem solving competition. Mr. Dr. Coach Rhodes can solve four more problems than twice the number of Coach South. If Mr. Dr. COach Rhodes has solved twenty problems, how many problems has Coach South solved?

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.