How do I find the beginning inventory for an individual product when the ending inventory of finished goods for the previous period consists of three products? Or am I doing this wrong?

(Reference below. Inventory - Finished Goods consists of the sum of three different products including the individual product which I must find the beginning inventory)

(The production budget below is the table for ITEM 1. The value I'm trying to solve is the July beginning inventory amount)

ITEM 2

ITEM 3

Target inventories are consistent for all 3 items (50% of next months sales in units).

Cost for each item:

ITEM 1	$ 279.99
ITEM 2	$ 59.99
ITEM 3	$ 39.99

Balance Sheet as at 31 June, 2022 Assets Cash Accounts receivable Inventory - Direct Materials Inventory Inventory - Finished Goods Land Property, Plant & Equipment Less Accumulated Depreciation Total Assets Liabilities and Stockholders' equity Accounts payable Bank Loan Share Capital Retained earnings Total Liabilities and Stockholders' equity $ 45,015 $ 113,650 54,275 79,150 $ 750,000 $ 160,000 -$ 8,000 $ 1,194,090 $ 42,500 $ 525,000 $ 102,765 $ 523,825 $ 1,194,090 Production Budget July August September October November December January February March April May June TOTAL July February 80 80 80 80 80 80 400 400 400 400 400 400 2880 400 400 Budgeted sales volume (units) Target Ending Inventory - 50% of next month's sales (units) Total Finished Goods Required Less Beginning Inventory 40 40 0 40 120 40 120 40 120 40 120 40 40 120 40 200 280 40 200 600 200 200 600 200 200 600 200 200 600 200 200 600 200 200 600 200 200 3,080 200 200 600 200 400 200 Budgeted sales volume (units) 1600 1100 1160 1000 600 600 500 400 400 400 1160 1100 1100 1200 11320 1400 1400 Budgeted sales volume (units) 1000 1000 1200 1200 1200 1300 1300 1400 1400 1400 1400 1400 15200 1400 1400