Giải câu 3 trang 139 sách toán VNEN lớp 5 tập 2

$\frac{21}{11}\times \frac{22}{17}\times \frac{68}{63}=\frac{\not{21}\times \not{22}\times\not{68}}{\not{11}\times \not{17}\times \not{63}}=\frac{1\times 2\times 4}{1\times 1\times 3}=\frac{8}{3}$

$\frac{5}{14}\times \frac{7}{13}\times \frac{26}{25}=\frac{\not{5}\times \not{7}\times \not{26}}{\not{14}\times \not{13}\times \not{25}}=\frac{1\times 1\times 2}{2\times 1\times 5}=\frac{2}{10}=\frac{1}{5}$