Answer:
$15 each the smaller donations and $50 the greatest donation.
Explanation:
For every $16 of donations, person 1 and two donate $3 each, and person 3 donates $10. In $80, there are 5 times of $16 donations, so person 1 and two donate a total of 5*$3 = $15, and person 3 donates 5*$10 = $50.