Answer:
7/12
Step-by-step explanation:
You have 12 slices, 3 are red 4 are blue.
You have 3/12 chance to get a red slice, and a 4/12 chance to get a blue slice
Add them together and you get 7/12
To check your work add the chance to get red and blue slice and the chance to get 5 yellow slices (5/12)
7/12+5/12= 12/12
