To multiply 2 fractions, multiply the numerator with the numerator and the denominator with the other denominator.
$${\frac{{\mathtt{1}}}{{\mathtt{2}}}}{\mathtt{\,\times\,}}\left({\frac{{\mathtt{3}}}{{\mathtt{4}}}}\right) = {\frac{{\mathtt{3}}}{{\mathtt{8}}}} = {\mathtt{0.375}}$$
Hope this helps :)
