An equation can be used to represent a real-world situation where one number is unknown, not provided or may change. That number is replaced by a variable. Let’s say Kerry and her sister Moira were selling raffle tickets for a school fundraiser. Moira sold 51 tickets, and they sold 72 tickets in all. To find out how many tickets Kerry sold, we can make an equation with a variable: 51 (the number of tickets Moira sold) + x (the unknown number of tickets Kerry sold) = 72 (the total number of tickets sold). Any variable, from a to z, can be used to represent Kerry’s tickets here; it doesn’t have to be x.
Which of these situations could be written as an equation with one variable?
A
Penny picked 35 apples, Ben picked 22 and Sam picked 17. They picked 74 apples all together. Who picked the most apples?
B
Harriet and Lea found 9 four-leaf clovers on the baseball field in all. Harriet found 5 of them. How many clovers did Leah find?
C
There were 45 doughnuts at the snack table today. Tanisha brought 33 of them, and Doug brought 12. Where did Tanisha buy her doughnuts?
D
Lori bought the most T-shirts of anyone in her family. She bought 1 more T-shirt than Thea and 3 more than Pino. How many shirts did Lori buy?
