①28和7
②8和9
③63和27
④16和40
12﹣3.6= 12×0.5= 36×25%= ×6+=
+= ÷4= 0××5= 28÷1.25÷8=
①600﹣300÷20×5
②(4.8﹣3.8÷2)×0.3
③3.45×99×2+6.9
④(8+ )÷4
⑤ ÷9+ ×
⑥ ÷[ ×( - )]