\(n_{CO_2}=0,04\left(mol\right)\\Đặt:n_{CaCO_3}=a\left(mol\right);n_{MgCO_3}=b\left(mol\right)\left(a,b>0\right)\\ CaCO_3+2HCl\rightarrow CaCl_2+CO_2+H_2O\\ MgCO_3+2HCl\rightarrow MgCl_2+CO_2+H_2O\\ \Rightarrow\left\{{}\begin{matrix}100a+84b=3,68\\a+b=0,04\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,02\\b=0,02\end{matrix}\right.\\ \Rightarrow\%m_{CaCO_3}=\dfrac{0,02.100}{3,68}.100\approx54,348\%\\ \%m_{MgCO_3}\approx100\%-54,348\%\approx45,652\%\)