①4x-4=2
②
③7(x+ )=4.2
④=2.7:0.6
□O□O□=□(本)
□O□=□(本)
88+8.8= 90÷5= 0.1÷0.2= 0.12×0.8= 0.3²=
÷10= ×0.25= - = + = ×7÷ ×7=