Process costing -joint and by-products

I still cannot solve the following joint product question after watching your lecture video. How should I apportion joint cost to the joint products if there are opening and closing WIP in the joint process? Grateful if you can help solve the quetion below as I read many reference book but still cannot find a solution to it. XYZ plc, a paint manufacturer, operates a process costing system. The following details related to process 2 for the month of October: Opening work in progress 5000 litres fully complete as to transfers from process 1 and 40% complete as to labour and overhead, valued at £60000 Transfer from process 1 65000 litres valued at cost of £578500 Direct labour £101400 Variable overhead £80000 Fixed overhead £40000 Normal loss 5% of volume transferred from process 1,scrap value £2.00 per litre Actual output 30000 litres of paint X (a joint product) 25000 litres of paint Y (a joint product) 7000 litres of by-product Z Closing work in progress 6000 litres fully complete as to transfers from process 1 and 60% complete as to labour and overhead. The final selling price of products X, Y and Z are: Paint X £15.00 per litre Paint Y £18.00 per litre Product Z £4.00 per litre There are no further processing costs associated with either paint X or the by-product, but paint Y requires further processing at a cost of £1.50 per litre. All three products incur packaging costs of £0.50 per litre before they can be sold. Required:(a)Prepare the process 2 account for the month of October, apportioning the common costs between the joint products, based upon their values at the point of separation. I cannot balance the process 2 account...