Mainstream Corporation manufactures two products, I and II, from a joint process. A production run costs $20,000 and results in 500 units of I and 2,000 units of II. Both products must be processed past the split-off point, incurring separable costs of $5 per unit for I and $10 per unit for II. The market price is $25 for I and $20 for II. Required: a. Allocate joint production costs to each product using the physical units method. b. Allocate joint production costs to each product using the net realizable value method.