3.5×[6.8-(1.6+3.6÷0.9)]÷84=3.5÷84×[ 6.8-(1.6+4)]=0.5÷12×[6.8-5.6]=0.5×(1.2÷12)=0.5×0.1=0.05
3.5×[6.8-(1.6+3.6÷0.9)]÷84=3.5×[6.8-(1.6+4)]÷84=3.5×(6.8-5.6)÷84=3.5×1.2÷84=0.5×7×0.1×12÷84=0.5×0.1×84÷84=0.05×1=0.05