Three salesmen work for the same company, selling the same product. and, although they are all paid on a weekly basis, each salesman earns his paycheck differently. salesman a works strictly on commission. he earns $65 per sale, with a maximum weekly commission of $1,300. salesman b earns a weekly base salary of $300, plus a commission of $40 per sale. there are no limits on the amount of commission he can earn. salesman c does not earn any commission. his weekly salary is $900. suppose salesmen a and b have the same number of sales and earn the same amount in week 4 of this month. how many sales must they both have had?