Lana is deciding whether or not to buy a pool pass for the summer. A pass costs $40 and $1 for admission each day, which is shown by the equation y = d + 40. Without a pass, the cost is $5 a day, which is shown by the equation y = 5d. Use the system of equations to find the number of days, d, for which the cost will be the same whether she decides to get a pass or not.