Their common denominator is 15. Hope it helps! :) If you could vote my answer as the brainliest, that would be awesome! :)
Step-by-step explanation:
<h2>This is a monster question I don't think anyone solve it for only 5 points</h2>
Answer:

Step-by-step explanation:


We have been given that Sterre charges $35 to file tax returns, but files for free if she only needs the easiest form. Also, she donates $2 to clean water projects per tax return she files.
Further we know that Sterre charged $7,245 and made a donation of $1,242 this year for the tax returns she filed.
Let x be the number of free income tax returns and y be the number of $35 income tax returns.
Therefore, we can set up:

Since she donates $2 for each return that she files, therefore, we can set up:

Therefore,
Sterre filed 414 tax returns for free and filed 207 tax returns for $35.