Mike earns $8 for each hour he works plus a 3% commission on his total daily sales. His daily earnings, P, can be determined using the equation 8h + 0.03d where h represents the number of hours worked and d represents his total daily sales in dollars. On Monday, Mike worked 4 hours and had $4,000 in total sales. He worked 6 hours on Tuesday and had $15,000 in total sales. How much more did Mike earn on Tuesday than on Monday?