4/5 + 1/8 =

$${\frac{{\mathtt{4}}}{{\mathtt{5}}}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{8}}}}$$

$${\frac{\left({\mathtt{32}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}}\right)}{{\mathtt{40}}}}$$

$${\frac{{\mathtt{37}}}{{\mathtt{40}}}}$$

If you want the result in fraction form, express both fractions over a common denominator:

4/5 = 4*8/(5*8) = 32/40

and

1/8 = 1*5/(8*5) = 5/40

Now you have 4/5 + 1/8 = 32/40 + 5/40 = 37/40

.