Cathy likes to wear 2 ribbons, each a different color. If she has 6 ribbons each of a different color, how many combinations of 2 different-colored ribbons can she select to wear?
- 3
- 6
- 12
- 15
- 36
Hint
Keep in mind that wearing one red ribbon and one blue ribbon is the same as wearing a blue one and a red one. You should count that combination only once. To save writing out names of colors, you could think of the ribbons as being numbered 1 to 6. How many combinations can Cathy wear that use ribbon 1? Ribbon 2?
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