From this scenario, we understand that the total fee for renting floor space at the flea market is composed of a base fee plus an additional charge for any extra square yardage beyond the standard area.
Breaking it down, we have:
1. A base fee of $200 per month. This is a constant rate that is charged irrespective of the amount of floor space rented.
2. A standard area of 12 square yards which is covered by the base fee. Hence, if you only rent this much space, you would only pay the base fee.
3. Beyond the standard area of 12 square yards, each extra square yard of floor space rented incurs an additional cost of $10.
Thus the number 10 in the equation refers to the cost incurred for each extra square yard of floor space rented beyond the standard area. In other words, it represents "the cost per extra square yard of floor space rented."
Please note that if your rented space does not exceed the standard area, you would not pay this cost; it only applies if you rent space more than the 12 square yards which is the standard area.