5(y-4)-7(7-y)=12-3(9-y)
5y-20-49+7y=12-27+3y
12y-3y=12-27+20+49
9y=54
y=6
〔15-(9分之7+6分之5-3分之1-18分之11)×18〕÷(-5分之6)
={15-(14+15-6-11)}×-6分之5
={15-14-15+6+11}×-6分之5
=3×-6分之5
=-2分之5