Answer: 1/4
Step-by-step explanation:
If you think of the original cake in terms of twelfths, then 4/12 are left over, and you eat a quarter of 4/12, which is 1/12. That means 3/12 = 1/4 of the original cake is left over.
You could also multiply 1/4 * 1/3 = 1/12 which is the amount you ate, and subtract that from 1/3 to get the amount left:
1/3 - 1/12 = 4/12 - 1/12 = 3/12 = 1/4.
