\[\boxed{\mathbf{777\ (777).}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\textbf{а)}\ \frac{5}{3} = 1 + \frac{2}{3} = 1\frac{2}{3}\]
\[\frac{8}{3} = 2 + \frac{2}{3} = 2\frac{2}{3}\]
\[\frac{9}{2} = 4 + \frac{1}{2} = 4\frac{1}{2}\]
\[\frac{21}{11} = 1 + \frac{10}{11} = 1\frac{10}{11}\]
\[\textbf{б)}\ \frac{64}{15} = 4 + \frac{4}{15} = 4\frac{4}{15}\]
\[\frac{43}{12} = 3 + \frac{7}{12} = 3\frac{7}{12}\]
\[\frac{80}{9} = 8 + \frac{8}{9} = 8\frac{8}{9}\]
\[\frac{78}{25} = 3 + \frac{3}{25} = 3\frac{3}{25}\]