olby and Sarah sold newspapers this past summer. Colby earned $4.50 for each newspaper he sold. Sarah's earnings were $35 less than Colby's at the end of the summer. The following expression shows Sarah's earnings:


4.50y − 35


In the expression, what does the variable y represent?


Sarah's earnings at the end of the summer

Colby's earnings at the end of the summer

The number of newspapers that Sarah sold

The number of newspapers that Colby sold