So there's 6 bottles and each bottle costs 3.60 but there's 4 cases.
So first multiply the number of bottles which is 6 with the cases which is 4.
6 x 4 = 24,so there's 24 bottles.Now multiply the price of the bottles time 24.
24 x 3.60 = 86.4.So the person that bought that will have to pay 86.4.Man those things are expensive.
Hope this helps :D