2600-7210÷35=2600-（7000÷35+210÷35）=2574【1/2-（3/4-3/5)】÷7/10=1/2)÷7/10-3/4÷7/10-3/5÷7/10=10/14-15/14-6/7=-17/1434.5乂8.23+1.77乂334.5=34.5*8.23+1.77*(300+34.5)=34.5*10+1.77*300=876以上仅供...