To add these two mixed numbers, we first need to convert them into improper fractions:

3/10 = 3/10
8 19/20 = (8 * 20 + 19) / 20 = 159/20

4 2/15 = (4 * 15 + 2) / 15 = 62/15

Now, we add the two improper fractions:

159/20 + 62/15

To add these two fractions, we need to find a common denominator. The least common multiple of 20 and 15 is 60.

So, we rewrite the fractions with a common denominator of 60:

159/20 = 477/60
62/15 = 248/60

Now, add the fractions:

477/60 + 248/60 = 725/60

Now, we need to convert the improper fraction back to a mixed number:

725/60 = 12 5/60 = 12 1/12

Therefore,
8 19/20 + 4 2/15 = 12 1/12