Let's walk back the poblem a bit.
We know that every square meter of ceiling requires 10.75 tiles. How many tiles would 10 square meters need?
We can consider that question as the following statement: "1 is to 10.75 as 10 is to x".
This leads to the following equation to obtain the value of x:

Now, what if instead of 10 square meters of ceiling we want to find out how many tiles are needed for a square meters of ceiling? The equation becomes:

And so, the answer is 10.75*a.