You've decided you want a plant for your room. At the gardening store, there are 4 different kinds of plants (tulip, fern, cactus, and ficus) and 4 different kinds of pots to hold the plants (clay pot, plastic pot, metal pot, and wood pot). If you randomly pick the plant and the pot, what is the probability that you won't get a clay pot or a cactus?
There are 4×4 = 16 different combinations of plant and pot. Of those, 7 are either clay pot or cactus. Thus the probability you won't get a clay pot or a cactuis is 9/16.