Answer:
The number of different choices is 720.
Step-by-step explanation:
The sales representative must visit six cities.
The visits of cities are independent.
Number of choices for the first visit: 6 possibilities
Number of choices for the second visit: 5 possibilities (He just visited one city, the sales representative don't have to go again)
Number of choices for the Third visit: 4 possibilities
Number of choices for the fourth visit: 3 possibilities
Number of choices for the Fifth visit: 2 possibilities
Number of choices for the Sixth visit: 1 possibilities
To count all the possibilities we have to multiple all of them:
6x5x4x3x2x1=720 different choices
