Since our denominators match, we can add the numerators.
1 + 4 = 5
That gives us the sum, which is
Now, do we need to simplify this fraction?
First, we attempt to divide it by 2...
Nope! So now we try the next greatest prime number, 3...
Nope! So now we try the next greatest prime number, 5...
Are both the numerator and the denominator evenly divisible by 5? Yes! So we reduce it:
Let's try dividing by that again...
No good. 5 is larger than 1. So we're done reducing.
There you have it! Here's the final answer to 1/5 + 4/5