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)