Tom ate 2/3 of the bread.
In adding fractions, there are three steps to follow.
Step 1. make sure that the denominators are the same.
1 3
---- + -----
6 6
Since both of our denominators are the same. We proceed to step 2.
Step 2. Add the numerators and place them above the denominator.
1 + 3 4
------- = ----
6 6
Step 3. Simplify the fraction.
4 2
---- = ----
6 3
The initial fraction is simplified by dividing both numerator and denominator by 2.