Madison bought an empty lot for $2,000 and later sold it for a 25% profit. how much did madison sell the lot for?

It is absolutely important to look at all the information's given in the question. Those information's would be required to solve the problem.
Amount at which Madison bought the empty plot = $2000
Percentage of profit made on selling = 25%
The amount of profit made by Madison = (25/100) * 2000
                                                               = 25 * 20
                                                               = 500 dollars
Amount at which Madison sold the empty lot = (2000 + 500) dollars
                                                                       = 2500 dollars
So Madison sold the empty lot at the rate of $2500. I hope this is the answer you were looking for and the procedure for doing such problems is also clear to you.

She should use 12/3 to measure