Answer:
750mL
Step-by-step explanation:
According to this question, a container which has the capacity to hold 3 L water already has 2.25 L water in it. This means that the container needs (3 - 2.25) = 0.75L to get filled up completely.
However, this question needs the volume of water needed to fill the container in milliliter (mL). To do this, we say;
1L = 1000mL
0.75L = 0.75 × 1000
= 750mL
Therefore, 750mL of water can still be added to fill up the container completely.