=IF(X<1500,X*3%,IF(X<7500,X*10%-100,IF(X<20000,X*20%-600,"")))
把公式中的X，换成你的单元格索引（例如：A1）即可
更新一下：
=LOOKUP(A1,{0,1500,4500,9000,35000,55000,80000,10000000},{0,0.03,0.1,0.2,0.25,0.3,0.35,0.45})*A1-LOOKUP(A1,{0,1500,4500,9000,35000,55000,80000,10000000},{0,0,100,500,1000,2000,5000,10000})
