Stream of consciousness rationale: 13 weeks have 13 * 7 = 91 days. For 91 days the bus system carries 1,200,000 * 91 = 109,200,000 people.
The question and answer pair are described below.
Q: The city's bus system carries 1,200,000 people each day. How many people does the bus system carry for 13 weeks?
A: 109200000