A customer can choose one of three amplifies, one of two compact disc players and one of five speaker models for an entertainment system. How do you determine the number of possible system configurations?

For <b>each</b> of these 3 options, you have 2 options for the CD players, which lets you with $3 \cdot 2 = 6$ options.
And for <b>each</b> of these options, you have 5 options for the speakers, which lets you with $6 \cdot 5 = 30$ final options.