The way to determine bacteriostatic or bacterial is by using a micorscope
All you have to do is write your question and someone will answer. For example, instead of writing "I do not understand how I find answers on here" you would ask something like what is 9*5? Then 2 people will see your question and answer. There are no pre-recorded answers, everything happens live. Hope this helps!
So it is really easy to solve firstly we can see how much does the first 10 boxes make which makes around 75$ obviously. Secondly 55$ for the next 10 boxes.
So for now we can simply calculate that we have spent around 130$ which means 20 boxes. The remaining money left is 18$ so we can buy 18/4.5 = 4 only 4 boxes with that money. Hence a total of 24 boxes.