how do you enter a fraction?
I'll just quickly show you another example
3 1/4 minus 7 4/9 would be done like this:
(3+1/4) - (7+4/9)=
it's the ÷ button.
Example fraction addition: 1/3 + 2/5
$${\frac{{\mathtt{1}}}{{\mathtt{3}}}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{2}}}{{\mathtt{5}}}}$$