Zoe's Fish tank holds 27 L of water, so this is the capacity of the tank. On the other hand, Zoe uses a 3L container in order to fill the tank, so the question is how many times does she have to fill the three litter container in order to fill the fish tank? Let's solve this as follows:
First time:
She pours 3L
Second time:
She pours another 3L, but she previously poured 3L, so she has poured 6L
Third time:
She pours another 3L, but she previously poured 6L, so she has poured 9L
Fourth time:
She pours another 3L, but she previously poured 9L, so she has poured 12L
Fifth time:
She pours another 3L, but she previously poured 12L, so she has poured 15L
Sixth time:
She pours another 3L, but she previously poured 15L, so she has poured 18L
Seventh time:
She pours another 3L, but she previously poured 18L, so she has poured 21L
Eighth time:
She pours another 3L, but she previously poured 21L, so she has poured 24L
Ninth time:
She pours another 3L, but she previously poured 24L, so she has poured 27L
According to this, she needs to pours the 3L container nine times in order to fill the fish tank. This can also be solved dividing 27L/3L= 9
