\[\boxed{\mathbf{564\ (564).}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ 43,3\ :9 = 4,8(1) \approx 4,8\]
\[2)\ 78,32\ :18 = 4,35(1) \approx 4,4\]
\[3)\ 38\ :11 = 3,(45) \approx 3,45\]
\[4)\ 10\ :18 = 0,(5) \approx 0,56\]
\[5)\ 5\ :9 = 0,(5) \approx 0,556\]
\[6)\ 64,45\ :19 = 3,3921\ldots \approx\]
\[\approx 3,39\]
\[7)\ 90\ :22 = 4,(09) \approx 4,091\]
\[8)\ 65\ :23 = 2,(826086956) \approx\]
\[\approx 2,8261\]
\[\boxed{\mathbf{564.}\mathbf{\ }}\]
\[\frac{7,8 + x}{2} = 7,2\ \ \ \ \ \ \]
\[7,8 + x = 7,2 \cdot 2\]
\[7,8 + x = 14,4\]
\[x = 14,4 - 7,8\]
\[x = 6,6.\]
\[Ответ:\ \ 6,6.\]