(1) 税后算税前个税公式=MAX[（税后工资-3500-速算扣除数）/（1-速算扣除数相应的税率）+3500]+个人负担部份，
=ROUND(MAX((J4-3500-5*{0,21,111,201,551,1101,2701})/(1-5%*{0.6,2,4,5,6,7,9})
(2) 个税=ROUND(MAX((计税工资-3500)*{3;10;20;25;30;35;45}%-5*{0;21;111;201;551;1101;2701},0),2)
(3) 倒推税前1=MAX((实发-3500-{0,105,555,1005,2755,5505,13505})/(1-{3,10,20,25,30,35,45}%)+3500,实发)+SUM(扣除的几险几金)
(4) 倒推税前2=MIN((税金+{0,105,555,1005,2755,5505,13505})/{3,10,20,25,30,35,45}%)+3500+SUM(社保)
即=MIN((税金+{速算扣除数})/{税率}%)+起征点+SUM(按规定扣除的几险几金)
