From the statement of the problem, we know that each participant:
• pays $14 to enter the race,
,
• receives a T-shirt that cost $3.50 to the organizers.
The earnings minus the cost of the T-shirts will be donated to charity, so for each participant, the donation will be $14 - $3.50. So the proportion of the entry fee paid by each runner that would be donated to charity is:
Answer
A. ($14.00 - $3.50) / $14.00