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…