7. Приведите к наименьшему общему знаменателю дроби: а) \(\frac5{16}\) и \(\frac7{12}\); б) \(\frac2{21}\) и \(\frac3{14}\); в) \(\frac7{15}\), \(\frac5{18}\) и \(\frac{11}{30}\).

а) НОЗ\((16,12)=48\): \(\frac5{16}=\frac{15}{48}\), \(\frac7{12}=\frac{28}{48}\).

б) НОЗ\((21,14)=42\): \(\frac2{21}=\frac4{42}\), \(\frac3{14}=\frac9{42}\).

в) НОЗ\((15,18,30)=90\): \(\frac7{15}=\frac{42}{90}\), \(\frac5{18}=\frac{25}{90}\), \(\frac{11}{30}=\frac{33}{90}\).

Ответ: а) \(\frac{15}{48}\) и \(\frac{28}{48}\); б) \(\frac4{42}\) и \(\frac9{42}\); в) \(\frac{42}{90}\), \(\frac{25}{90}\) и \(\frac{33}{90}\).