1. **State the problem:** John has three types of activities to choose from for his evening: reading a book, watching a video, or going to the movies. 2. **Given data:** - Number of books = 3 - Number of videos = 7 - Number of movies = 10 3. **Formula used:** To find the total number of different choices, we add the number of options for each activity because John can only choose one activity. $$\text{Total choices} = \text{Number of books} + \text{Number of videos} + \text{Number of movies}$$ 4. **Calculate:** $$\text{Total choices} = 3 + 7 + 10$$ 5. **Simplify:** $$\text{Total choices} = 20$$ 6. **Answer:** John has 20 different choices for how to spend his evening.