It takes 20 days for a batch of garments to be made by factory A alone, but 42 sets can be made by factory B every day. When the two groups complete this batch of parts together, factory B has made 70% of all the parts. How many sets of this batch of garments are there in total?
一批服装，如果甲厂单独做要20天，而由乙厂做每天可以做42套，当两组共同完成这批零件时，乙厂做了全部的70%，这批服装共多少套？
<result>3_600</result>