H先说一说各题的运算顺序,再用递等式计算。$$1) 5 0 0 - ( 2 3 5 0 + 1 5 0 ) \div 2 0 \times 2 \\ =500-2500 \div 20 \times 2 \\ =500-125m \\ =500-250 \\ =2.50 $$(2)$$ 1 2 5 \times \left[ 1 2 3 - ( 5 5 - 1 2 ) \right] \div 1 ...
,5D0$$ 320 \div 8=40 N a O H = N a $$$ 5=25 250+5 \times 500 $$40 14000 31 (43$$ 40400 62-4-32=31 $$34$$ 43-43 $$$ 11 48 \div 2=34 $$1 33$$ 99 \div 3=33 12 $$一找会称.$$ 66 \div 2=33 $$ 33 cF 140 44 b4$$ 13 \times 3=39 20...
$$ 4 4 \times 2 5 $$(H)天天$$ 15+25=40 260+240=500 3 2 0 0 \div 4 \div 2 5 $$40 500$$ 40-23=17 300-150=150 $$17 150$$ 47+33=80 180+290=470 $$80 470$$ 54-26=28 450-270=180 7 3 8 + 2 9 3 + 6 2 + 1 0 7 $$28 180$$ 70+19=84 1...