Answer: 12 peanut butter cookies
Explanation:
Fred had made 10 dozen cookies which means he made:
= 10 * 12
= 120 cookies
Out of those, 1/4 were peanut butter:
= 120 * 1/4
= 30 peanut butter cookies
He burned 3/5 of the peanut butter cookies:
= 30 * 3/5
= 18 cookies were burnt
The amount let is therefore:
= 30 - 18
= 12 peanut butter cookies