1) 80×(1-40%) =80×60% =48千米2) 90÷30% =300吨3)1200÷(1+25%) =1200÷1.25 =960人4) 40×(1-20%) =40×0.8 =32千克
(1-40%) x 80=?
? x 30%=90
? x (1+25%)=1200
40/(1+20%)=?
