$\frac{23}{14}$ × $\frac{6}{13}$ -$\frac{9}{14}$ × $\frac{6}{13}$
= $\frac{6}{13}$ × ( $\frac{23}{14}$ - $\frac{9}{14}$ )
= $\frac{6}{13}$ × 1
= $\frac{6}{13}$
$\frac{7}{4}$ × $\frac{11}{21}$ + $\frac{11}{21}$ ×$\frac{5}{4}$
= $\frac{11}{21}$ × ( $\frac{7}{4}$ + $\frac{5}{4}$ )
= $\frac{11}{21}$ ×3
=$\frac{11}{7}$
$\frac{6}{7}$ × $\frac{16}{15}$ × $\frac{7}{6}$ ×$\frac{21}{32}$
= ($\frac{6}{7}$ ×$\frac{7}{6}$ ) × ( $\frac{16}{15}$ × $\frac{21}{32}$ )
= 1 × $\frac{7}{10}$
= $\frac{7}{10}$
Cho mk ctlhn nha ! <3
