Answer:
9/12 or simplified as 3/4
Explanation:
We are given 3 fractions that we have to add because the question says "What fraction of the can did she use in all?"
First: Write down

Then: We can't just add up all these fractions, we need a LCM. The LCM (Least Common Multiple) We need all the denominators (3, 4, and 6) to be the same. To do that we need to find a number that they can multiply to get. Let's find out all the multiples of each number: (just write the first 5 down because most of the time we can find it easily from this list)
3: 3, 6, 9, 12, 15
4: 4, 8, 12, 16, 20
6: 6, 12, 18, 24, 30
After: just change all the fractions one at a time by whatever you multiply the bottom number to get 12, do it to the top:



Finally we get to add everything up to get:

(simplified as 3/4)