Ответ:

а) \(\left(\frac49+\frac5{12}\right)\cdot\frac{18}{31}=\frac{31}{36}\cdot\frac{18}{31}=\frac12\).

б) \(\frac6{25}\cdot\left(\frac{11}{15}-\frac9{20}\right)=\frac6{25}\cdot\frac{17}{60}=\frac{17}{250}\).

в) \(\left(4-3\frac7{15}\right)\cdot\frac58=\frac8{15}\cdot\frac58=\frac13\).

г) \(\left(5-4\frac47\right)\cdot\left(7\frac16-6\frac5{12}\right)=\frac37\cdot\frac34=\frac9{28}\).

д) \(\left(1\frac1{24}-\frac5{12}\right)\cdot\left(4\frac18-3\frac5{24}\right)=\frac58\cdot\frac{11}{12}=\frac{55}{96}\).

е) \(\left(1\frac2{15}-\frac{11}{15}\right)\cdot\left(5\frac3{18}-4\frac1{27}\right)=\frac25\cdot\frac{61}{54}=\frac{61}{135}\).

Ответ: а) \(\frac12\); б) \(\frac{17}{250}\); в) \(\frac13\); г) \(\frac9{28}\); д) \(\frac{55}{96}\); е) \(\frac{61}{135}\).