David owns a decorative bowls & dishes store. He sells a set of plates (including 8 plates) for $25. Considering that he pays $2 for each plate, and he has a fixed cost of $45,000.

2. How many sets of plates need to be sold to break even?
4. Find the break-even revenue.
6. He recently hired an assistant; this is expected to cost $35,000 and there is a 15% increase in the variable cost per each plate. Based on the additional cost, calculate both break-even revenue and break-even volume.