\[\boxed{\mathbf{1.}}\]
\[1 = \frac{3}{3}\]
\[2 = \frac{6}{3}\]
\[4 = \frac{12}{3}\]
\[16 = \frac{48}{3}\]
\[\boxed{\mathbf{2.}}\]
\[\textbf{а)}\ \]
\[4\frac{2}{3} = \frac{3 \cdot 4 + 2}{3} = \frac{14}{3}.\]
\[\textbf{б)}\ 3\frac{1}{4} = \frac{3 \cdot 4 + 1}{4} = \frac{13}{4}\ \]
\[4\frac{3}{5} = \frac{4 \cdot 5 + 3}{5} = \frac{23}{5}\]
\[1\frac{5}{9} = \frac{9 \cdot 1 + 5}{9} = \frac{14}{9}\]
\[2\frac{11}{12} = \frac{12 \cdot 2 + 11}{12} = \frac{35}{12}\]
\[\boxed{\mathbf{3.}}\]
\[\textbf{а)}\ a\ :2 \cdot 5\ (цветов) - всего\ в\ \]
\[вазе.\]
\[\textbf{б)}\ b\ :100 \cdot 30\ (лисиц) - в\ \]
\[зверосовхозе.\]
\[\textbf{в)}\ c\ :20 = \frac{c}{20}\ (часть) -\]
\[аквариума\ заполнена\ водой.\]
\[\textbf{г)}\ d - d\ :7 \cdot 4\ (пирожков) -\]
\[осталось.\]
\[\boxed{\mathbf{4.}}\]
\[\textbf{а)}\ 348 \cdot x\]
\[x = 5720:\]
\[\textbf{б)}\ 19\ 852\ 400\ :y\]
\[y = 248:\]
\[\boxed{\mathbf{5.}}\]
\[3\frac{9}{7} = 4\frac{2}{7}\]
\[9\frac{2}{5} = 8\frac{7}{5}\]
\[3 = 2\frac{7}{7}\]