First, we need a common denominator. The lowest number with both 3 and 4 (our current denominators) as factors is 12. To make the denominator of each fraction 12, we will use multiplication.
(2/3 * 4/4) + (1/4 * 3/3)
8/12 + 3/12
Now, we can simply add the numerators.
8/12 + 3/12 = 11/12