Ah, Alcorn thought, this is easy. If you increase advertising from $800 up to $2000, then sales go up from $10,500 to $16,500. So an increase in advertising expenses of $1200 results in an increase in sales of $6000. Her gross profit margin on the fashion goods she carried in her tiny boutique was 50. Find the increased gross profit by multiplying the 50, by the increase in sales.