(2+3/4 ) kg = 11/4 kg
$$2\frac{3}{4}*\frac{1}{2} = 1\frac{3}{8} [ kg ]$$
$$\left({\mathtt{2}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{3}}}{{\mathtt{4}}}}\right){\mathtt{\,\times\,}}\left({\frac{{\mathtt{1}}}{{\mathtt{2}}}}\right) = {\frac{{\mathtt{11}}}{{\mathtt{8}}}} = {\mathtt{1.375}}$$
(2+3/4 ) kg = 11/4 kg
$$2\frac{3}{4}*\frac{1}{2} = 1\frac{3}{8} [ kg ]$$