"There is no need to apologise, your Q is not basic or anything like that, we all struggle with this stuff daily! I just googled and your vat is 20% so if the invoice has many lines on it just take the total of each line and multiply it by 1.2 and…"
"I am still not quite sure about your Q. As postage is freight is a cost of sale why not just take the invoice total inc the postage and divide it by how many items you bought, that would be your cost.
"Hi I dont understand your VAT question really, can you expand on it? I think with your purchases you need to account for the bank charges and fees as per the example given below as they are all a cost to your business and affect your P and L, so…"