This video will help you understand purchase orders, common features and how to complete one including calculation goods total, discounts, subtotals and the amount to pay.
Download template:
https://drive.google.com/open?id=1_u1PLUijwOWsoUxG2AXb3UjqgidZY5ej
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https://time2resources.co.uk/Pearson-BTEC-Level-1-2-Tech-Award-Enterprise