Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.
So, we multiply 4 by 4, and get 16, then we multiply 5 by 4 and get 20.
Now for the second term. You multiply 2 by 5, and get 10, then multiply 5 by 4 and get 20.
We now have a new problem, that looks like this:
Since our denominators match, we can add the numerators.
16 + 10 = 26
That gives us the sum, which is
Now, do we need to simplify this fraction?
First, we attempt to divide it by 2...
Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:
Let's try dividing by that again...
Nope! So now we try the next greatest prime number, 3...
Nope! So now we try the next greatest prime number, 5...
Nope! So now we try the next greatest prime number, 7...
Nope! So now we try the next greatest prime number, 11...
No good. 11 is larger than 10. So we're done reducing.
There you have it! Here's the final answer to 4/5 + 2/4