Shari wrote the numbers from 1 to 16 on a card.

Next, she crossed out all the numbers which are factors of 80.

Then, she crossed out all the numbers which are multiples of 3.

How many numbers were not crossed out?

Factors of 80: 1,2,4,5,8,10,16,20,40,80

so we cross out 1,2,4,5,8,10,16

the first 5 multiples of 3 are: 3,6,9,12,15

so we cross out those number and then we are left with 7, 11, 13 and 14

the answer is: 4 numbers were not crossed out