You can convert 2/3 into a fraction that makes adding a lot easier.
Since 3 times 2 is equal to 6, you can multiply the numerator and denominator of 2/3 by 2 to get 4/6.
From there, you add 4/6 + 5/6 to get 9/6.
Since both 9 and 6 are divisible by 3, you can simplify the fraction to 3/2.
Your final answer would be 3/2
Which can also be formatted as 1 1/2 or 1.5