Evelyn ate: 1/2 = 2/4 cup
Brother ate: 1/4 cup
Together they ate: 3/4 cup
2 2/3 - 3/4 = 1 11/12
Because:
First you have to make 2 2/3 into a fraction instead of a whole in a fraction so:
2 2/3 = 8/3
Then, you have to find a common denominator between 8/3 and 3/4 which is 12. So, you multiply 8/3 by 4 and 3/4 by 3 to get 32/12 and 9/12. Now, do 32/12 - 9/12 which gives you 23/12. The denominator stays the same because the numbers are the same. Finally, you simplify which is 1 11/12.