13. The Carter Company makes products A and B in a joint process from a single input, R. During a typical production run, 50,000 units of R yield 20,000 units of A and 30,000 units of B at the split- off point. Joint production costs total $120,000 per production run. The unit selling price for A is $4 and for B is $4.80 at the split-off point. However, B can be processed further at a total cost of $46,000 and then sold for $6.00 per unit. If product B is processed beyond the split-off point, the change in operating income from a production run (as compared to selling B at the split-off point) would be