If there are 20 children that went to eat lunch, and 14 of them ate fish burgers, and 10 ate chicken burgers, you could make a line graph with 20 points and color the kids who ate fish burgers yellow and the one who ate chicken burgers blue. The green where they overlapped, and 10 of them over lapped, meaning that 10 children ate both fish and chicken burgers. Hope I helped!
