Archie received his medical receipt from his doctor, and he needs to take antibiotics three times a day. If antibiotic costs $3 each and he needs to take it for a week, how much money does he need to buy the antibiotics? Let's answer step by step:
Archie needs $3 x 3 = $9 per day to buy 3 antibiotics. Therefore Archie needs $9 x 7 = $63 to buy antibiotics that will last for a week. The answer: 63.