8.8×1.25×100÷4 =11×100÷4 =1100÷4 =275 （0.39÷3-0.1）÷3分之1 =（0.13-0.1）×3 =0.03×3 =0.09 12.5-5分之1X+5分之9X=20.5 9/5X-1/5X=20.5-12.5 8/5X=8 X=5
