Cai collected most and Mark collected least
Solution:
Let Jen collected be "x"
Given that,
Mark collected 2/3 as much as Jen
Also given that,
Cai collected 2 1/2 times as much as mark
Therefore,
Who collected the most? Who collected the least?
Jen collected = x
Mark collected = 0.67x
Cai collected = 1.67x
Thus,
1.67x > x > 0.67x
Thus, Cai collected most and Mark collected least