11/12+7/10

You need to get the same denominator by multiplying the numerators and deniminators by the other denominator. $$\left({\frac{\left({\mathtt{11}}{\mathtt{\,\times\,}}{\mathtt{10}}\right)}{\left({\mathtt{12}}{\mathtt{\,\times\,}}{\mathtt{10}}\right)}}\right){\mathtt{\,\small\textbf+\,}}\left({\frac{\left({\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{12}}\right)}{\left({\mathtt{10}}{\mathtt{\,\times\,}}{\mathtt{12}}\right)}}\right)$$ You then have $$\left({\frac{{\mathtt{110}}}{{\mathtt{120}}}}\right){\mathtt{\,\small\textbf+\,}}\left({\frac{{\mathtt{84}}}{{\mathtt{120}}}}\right)$$ which makes it easier to solve.