$\frac{11,2:9\frac{1}{3}-0,8}{1,25:2\frac{1}{2}+0,3}=\frac{\frac{112}{10}:\frac{28}{3}-0,8}{1\frac{1}{4}:\frac{5}{2}+0,3}=\frac{\frac{{\sout{112}}^4}{10}\cdot \frac{3}{{\sout{28}}^1}-0,8}{\frac{{\sout{5}}^1}{{\sout{4}}^2}\cdot \frac{{\sout{2}}^1}{{\sout{5}}^1}+0,3}=\frac{\frac{12}{10}-0,8}{\frac{1}{2}+0,3}=\frac{1,2-0,8}{0,5+0,3}=\frac{0,4}{0,8}=\frac{1}{2}$ $\frac{11,2:9\frac{1}{3}-0,8}{1,25:2\frac{1}{2}+0,3}=\frac{\frac{112}{10}:\frac{28}{3}-0,8}{1\frac{1}{4}:\frac{5}{2}+0,3}=\frac{\frac{{\sout{112}}^4}{10}\cdot \frac{3}{{\sout{28}}^1}-0,8}{\frac{{\sout{5}}^1}{{\sout{4}}^2}\cdot \frac{{\sout{2}}^1}{{\sout{5}}^1}+0,3}=\frac{\frac{12}{10}-0,8}{\frac{1}{2}+0,3}=\frac{1,2-0,8}{0,5+0,3}=\frac{0,4}{0,8}=\frac{1}{2}$

$1,2\cdot \frac{1}{2}=\frac{12}{10}\cdot \frac{1}{2}=\frac{12}{20}=\frac{6}{10}=0,6odp.D$