(x-6000)*5.55%-(x-6000-180-30-3)*30%-{x-[(x-6000)*5.55%]-(x-6000-180-30-3)*30%}*20%-x*3%-6000*6%*2=6000*(1+5%)
5.55%X-333-30%X+1863.9-(X-5.55%X+333-30%X+1863.9)*20%-3%X-720=6300
5.55%X-333-30%X+1863.9-20%X+1.11%X-66.6+6%X-372.78-3%X-720=6300
5.55%X-30%X-20%X+1.11%X+6%X-3%X=6300+333-1863.9+66.6+372.78+720
-40.34%X=5928.48
X=-592848/40.34
X=-29642400/2017
X=-14696.28161