Javier designs leather shoes at his workshop. he charges $45 for women's shoes and $50 for men's shoes. he needs to make $2,500 per week to meet his expenses. this situation can be given by 45x + 50y = 2,500, where x is the number of women's shoes and y is the number of men's shoes designed by javier. if he does not have any female customers during a particular week, how many male customers does he need to meet his expenses? (x 0, y 0, x and y take only integer values)

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.