28,8:13 5/7+6,6:2/3 все делим 1 11/16:2,25

[latex] frac{28,8: 13 frac{5}{7}+6,6: frac{2}{3} }{1 frac{11}{16}:2 frac{1}{4} } = frac{ frac{144}{5}* frac{7}{96} + frac{33}{5} *frac{3}{2} }{frac{27}{16}* frac{4}{9} }= frac{ frac{21}{10} + frac{99}{10} }{ frac{3}{4} } = frac{12}{ frac{3}{4} } =16[/latex]