Ответ: 1) [tex]\frac{2}{7}[/tex]

2)[tex]xy^3[/tex]

3)[tex]\frac{n^2}{m^4}[/tex]

4)[tex]1\frac{1}{2}[/tex]

Объяснение: 1) [tex]\frac{7a}{8b} *\frac{16b}{49a}= \frac{7}{8b} *\frac{16b}{49}= \frac{7}{8} *\frac{16}{49} = 7*\frac{2}{49}= \frac{2}{7}[/tex]

2)[tex]\frac{x^2}{y^4}*\frac{y^7}{x} =\frac{x}{y^4}*y^7=xy^3[/tex]

3)[tex]\frac{m^2}{n} :\frac{m^6}{n^3}=\frac{m^2}{n}*\frac{n^3}{m^6}= m^2*\frac{n^2}{m^6}= \frac{n^2}{m^4}[/tex]

4)[tex]\frac{11c}{13d} :\frac{22c}{39d}= \frac{11c}{13d}* \frac{39d}{22c} =\frac{11}{13d}*\frac{39d}{22} =\frac{11}{13}*\frac{39}{22}=11*\frac{3}{22}=\frac{3}{2}=1\frac{1}{2}[/tex]