0.4 liter means 400 ml (milliliter).
We know that 1 spoon is 5 ml. Thus, if each student takes out 2 spoons, then each student will take out 10 ml of water.
There are 22 students, so each student will take out 220 ml.
Thus, the milliliters of seawater that will be left after all 22 students have filled their containers is:
ml