Question

3/7-1/21
Как решить?

Answer 1

$frac{3}{7}-frac{1}{21}=frac{3*3}{7*3}-frac{1}{21}=$
$=frac{9}{21}-frac{1}{21}=frac{9-1}{21}=frac{8}{21}$
ответ: 8/21

Answer 2

3,7-1,21=3,70-1,21=2,49.