Question

помогите с номером 1

Answer 1

$a) \frac{21}{10} *\frac{5}{7} =\frac{3}{2} =1\frac{1}{2}\\\\ b)\frac{9}{2} *\frac{4}{21} =\frac{6}{7} \\\\ c)\frac{19}{4} *\frac{4}{1} -\frac{31}{14} *7=\frac{19}{1} -\frac{31}{2} =\frac{38}{2} -\frac{31}{2} =\frac{7}{2} =3\frac{1}{2}$