1
(72+79/3)×1/11=(216/3+79/3)×1/11={(216+79)/3}×1/11=(295/3)×(1/11)=295/33
2【3/4÷(4/5+1/4)-4/7】×9/11
=【3/4×{1/(4/5+1/4)}-4/7】×9/11
=【(3×1)/{4×(4/5+1/4)}-4/7】×9/11
=【3/(16/5+1)-4/7】×9/11
=【3/(21/5)-4/7】×9/11
=【3×(5/21)-4/7】×9/11
=【5/7-4/7】×9/11
=(1/7)×9/11
=9/77
行不?