Pg 647 (579) - Q21
The key to the problem is the phrase one or more. Because he
can select one or more of the three toppings, his options are expanded.
Choosing one topping yields 3 options, choosing two toppings also yields
3 options (nuts + whipped cream, nuts + cherries, or
whipped cream + cherries), and choosing all three toppings yields
one option. This is a total of 3+3+1=7 combinations or toppings for
Luis.