Cost of bottles that come in packs of 12 = 3 dollars It is already given in the question that i drink 3 bottles per day. So the cost of 3 bottles has to be determined first and then the number of bottles that is drunk in a week also has to be determined. after that the cost per week can be easily determined. Number of bottles drunk per day = 3 So The number of bottles drunk in a week = (3 * 7) bottles = 21 Now Cost of a pack of 12 bottles = 3 dollars Then Cost of 1 bottle = (3/12) dollars = (1/4) dollars = 0.25 dollars So The cost of 21 bottles = (21 * 0.25) dollars = 5.25 dollars So the cost per week as determined above is $5.25.
