Which of the following formulas best describes the merchandise purchases budgets (in units)? Inventory to purchase = Budgeting ending inventory (in units) + budgeted cost of sales for the period (in units) - budgeted beginning inventory (in units). Inventory to purchase = Budgeting beginning inventory (in units) + budgeted cost of sales for the period (in units) - budgeted ending inventory (in units). Inventory to purchase = Budgeting beginning inventory (in units) + budgeted cost of sales for the period (in units) + budgeted ending inventory (in units). Inventory to purchase = Budgeting ending inventory (in units) + budgeted costs of sales for the period (in units) + budgeted beginning inventory (in units). None of the above.