According to the comments, it seems that you are asking for an inequality to represent the given situation (the question wasn't very clear on that, so please let me know if this isn't it)
They need a total of $800 in fundraisers, which means that they need to earn AT LEAST $800 to reach their goal.
They are already given a donation of $530, and get $15 for every car washed. Let x represent the amount of cars washed.
The total amount of funds earned would be the donation added with the money earned from washing cars, which would be 15x.
Amount of money earned: 530 + 15x
They need at least a total of $800, thus we can use a greater than or equal sign to create the following equation:
530x + 15x ≥ 800
Let me know if you need any clarifications etc., thanks!
