①46×67-32×46 =46×(67-32) =46×35 =1610 ②1.25+7.8+0.75+2.2 =(1.25+0.75)+(7.8+2.2) =2+10 =12 ③25×8×4 =25×4×8 =100×8 =800 ④87500÷125÷8 =87500÷(125×8) =87500÷1000 =87.5