①0.4x+2x=21.6
②5x﹣8.4×50%=19.8
③0.5:x= :
+= ﹣= 24×= 5﹣=
30÷= += +0.25= ÷=
500-213= 10÷10%= 0.25+2.83= 1.25×0.8= 3.7-3.7÷3.7=
92-33= + = × = 9÷ = ( - )×20=
2x+×10=30 :x=: