Final answer:
Darryl ate 1/15 of the package of cookies.
Step-by-step explanation:
To find out how much Darryl ate, we need to calculate the amount of cookies he ate from the remaining package. First, let's find out how many cookies were in the original package. Since Darryl noticed there was 2/3 of the package left on the counter, we can say that he ate 1/3 of the package. Next, we need to find out how much he ate from the remaining 1/3 of the package. He ate 1/5 of the remaining package, so we can calculate it by multiplying 1/3 by 1/5.
1/3 x 1/5 = 1/15
Therefore, Darryl ate 1/15 of the package of cookies.