A charity is considering the possibility of having a benefit night at two different restaurants. The owner of the local Italian restaurant has offered to make a donation of $350 and $1 per diner that night. On the other hand, the owner of the Mexican restaurant has said he could contribute $50 plus $4 per diner. Based on the number of diners who have promised to participate in the event, it appears that each restaurant would donate the same total amount. How many diners promised to participate?