Answer: Total fish are 27, difference is 18
Explanation:
Given: one-third of the fish in Liam's fish tank were added today. Half of the other fish were a gift to Liam last week. the other 9 came from Liam's old fish tank.
To Find: Number of the fish in the tank, difference between the number of fish Liam had in his old tank and the number he has now.
Solution: Let the total fish in tank be = x
total fish added today =

Total fish left =
=

Fish gifted to him last week =

=

Fish left =
-


now,
fish left in the tank are =
fish from liam's old tank = 9 = fish left in the tank
= 9
=

Total fish in liam's new tank=

difference between the number of fish Liam had in his old tank and the number he has now
=

Total Fish in Liam's new tank are 27 and difference between the number of fish Liam had in his old tank and the number he has now is 18.