12.4÷5=
6.56÷3.2=
★64.8÷0.8=
(x-15)表示
5x表示
(x-15)×4表示
①772-317+128-283
②2.4÷( -20%)
③1-
④5.125× +2.875÷4
⑤
60÷80%= 75%+0.25= = =