Question: Grand Canyon Tours offers air and ground scenic tours of the Grand Canyon. Tickets for the 7 1 2 -hr tour cost $169 for an adult and $129 for a child, and each tour group is limited to 19 people. On three recent fully booked tours, total receipts were $2931 for the first tour, $3011 for the second tour, and $2771 for the third tour. Determine how many adults and how many children were in each tour.