①8和9
②12和36
③45和60
④24和40
12﹣3.6= 12×0.5= 36×25%= ×6+=
+= ÷4= 0××5= 28÷1.25÷8=
①﹣+-
②(﹣)×18×12
③2×1.5+4.5÷0.75
④69×9.9+6.9