Here's how to add
Since our denominators match, we can add the numerators.
1 + 3 = 4
The sum we get is
The last step is to reduce the fraction if we can.
To find out, we try dividing it by 2...
No good. So next you try the next prime number, which is 3...
No good. So next you try the next prime number, which is 5...
No good. 5 is larger than 4. So we're done reducing.
And we're done! Here's the final answer to 1/5 + 3/5