To solve this, you'd need to find the least common denominator (LCD) so that both fractions have the same number on the bottom. In this case, the first number that you could get with 5 and 3 was 15.
Next, you'd have to multiply the numerator by the same amount as the denominator, so that the fractions are proportionate. So, for 1/5, since we had to multiply 5 by 3 to get 15, we'd multiply 1 by 3 as well, giving us 3/15. Doing the same with 2/3, we'd get 10/15.
Then, you add the two fractions together (10/15 + 3/15 = 13/15).
Now, in any other case, you could probably simplify the fraction after you've solved the problem. If we got 12/15 instead of 13/15, then we could simplify that to 4/5, since both 12 and 15 are divisible by 3. But in this case, this is the simplest form of that fraction.
