(124x12一85x12)÷26
=39✘12✘(1/26)=12✘3✘13✘(1/13)✘(1/2)=12✘3✘(1/2)=6✘3=18
原式=39×12÷26×12=13×3×2×6÷26 =26÷26×18=18
