So we start with 1 bag of chips and we remove 1/4.
1 - 1/4 = 3/4
If 2/3 of the remaining chips are then removed, that means 1/3 will be left. To find out what 1/3 of 3/4 is, just multiply the numbers.
3/4 x 1/3 = 3/12
3/12 will simplify to 1/4, and that's your answer.