Ответ:
\(4\cdot\frac{5}{21}=\frac{20}{21}\).
\(24\cdot\frac{7}{12}=2\cdot7=14\).
\(\frac{16}{63}\cdot9=\frac{16}{7}=2\frac{2}{7}\).
\(36\cdot\frac{13}{48}=\frac{3}{4}\cdot13=\frac{39}{4}=9\frac{3}{4}\).
Ответ: 1) 20/21; 2) 14; 3) 2 2/7; 4) 9 3/4.
\(4\cdot\frac{5}{21}=\frac{20}{21}\).
\(24\cdot\frac{7}{12}=2\cdot7=14\).
\(\frac{16}{63}\cdot9=\frac{16}{7}=2\frac{2}{7}\).
\(36\cdot\frac{13}{48}=\frac{3}{4}\cdot13=\frac{39}{4}=9\frac{3}{4}\).
Ответ: 1) 20/21; 2) 14; 3) 2 2/7; 4) 9 3/4.