3[2(10-4)+2(10-15)] hola tu sabes como se procede para resolver esta operacion
$${\mathtt{3}}{\mathtt{\,\times\,}}\left[{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{6}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}{\mathtt{\,\times\,}}\left(-{\mathtt{5}}\right)\right] = {\mathtt{3}}{\mathtt{\,\times\,}}\left[{\mathtt{12}}{\mathtt{\,-\,}}\left({\mathtt{10}}\right)\right] = {\mathtt{3}}{\mathtt{\,\times\,}}\left({\mathtt{12}}{\mathtt{\,-\,}}{\mathtt{10}}\right) = {\mathtt{3}}{\mathtt{\,\times\,}}{\mathtt{2}} = {\mathtt{6}}$$
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