did you actually type \frac{2*5}{4*5}+\frac{3*4}{4*5}?
1. 2/3 = $${\frac{{\mathtt{2}}}{{\mathtt{3}}}} = {\mathtt{0.666\: \!666\: \!666\: \!666\: \!666\: \!7}}$$
6-(2/3)=$${\mathtt{6}}{\mathtt{\,-\,}}\left({\frac{{\mathtt{2}}}{{\mathtt{3}}}}\right) = {\frac{{\mathtt{16}}}{{\mathtt{3}}}} = {\mathtt{5.333\: \!333\: \!333\: \!333\: \!333\: \!3}}$$
2. $$12-3$$ = 9
12-5/9$${\mathtt{12}}{\mathtt{\,-\,}}{\frac{{\mathtt{5}}}{{\mathtt{9}}}} = {\frac{{\mathtt{103}}}{{\mathtt{9}}}} = {\mathtt{11.444\: \!444\: \!444\: \!444\: \!444\: \!4}}$$
Honestly, i have no idea what i done...