the question says,
the apartment caretaker puts 0.75L of chlorine into the swimming pool daily
the chlorine is sold in containers that holds 4L
so we should get the numbers of containers he should order in 120days.
first of all, lets get the total chlorine needed
total chlorine needed = the chlorine he pours daily X the number of days
total chlorine needed = 0.75 X 120 = 90L
to get the number of containers he should order
= 90/4
= 22.5
therefore the number of containers the he sholuld order in 120 days is 22 and half container.
