应纳增值税=（42000+1500+500+68000+1000)*17%/1.17-(10200-5000*17%-8000*17%)=113000*17%/1.17-(10200-850-1360)=16418.8-7990=8428.8 软件应退增值税=8428.8-(42000+1500+500+68000+1000)*3%/1.17=8428.8-2897.44=5531.36
