Question

2 upnon 5 * by 21 upon 4​

Answer 1

$\:\:\:\frac{2}{5} ×\frac{21}{4} \\ \\ = \frac{(2 \times 21)}{(5 \times 4)} \\ \\ = \frac{42}{20} \\ \\=\frac{21×2}{10×2}\\ \\=\frac{21}{10}\\ \\=2.1$