3.8-8.7×0.3+6.2-6.39=3.8-2.61+6.2-6.39=(3.8+6.2)-(2.61+6.39)=10-9=1
3.8一8.7×0.3+6.2一6.39=3.8一2.61+6.2一6.39=(3.8+6.2)一(2.61+6.39)=10一10=0