Total PnL under the Isolated Margin Trading Positions

So, I've been working through the articles and such to try and understand other elements of the platform and how things work etc. It's taken time, but I've managed to wrap my head around most of it.

Going through the "Isolated Margin Trading Positions" page I seem to have gotten stuck at "4. What is Total PNL?" as the given examples don't appear to be using the correct math?

From the page examples:

For example, here are the trade details of a BTCUSDT isolated pair:

Date Trade Quantity Execution Price

T+1 Buy 10 BTC 30,000 USDT

T+2 Sell 7 BTC 32,000 USDT

T+3 Sell 2 BTC 33,000 USDT

Assume the latest index price of BTCUSDT is 36,000.

Net Buy Quantity = 10 - 7 + 2 = 5 BTC

According to the info on the page:

*Net Buy Quantity = Quantity of Buy order position - Quantity of Sell positions (trade asset)

I don't get how the example ends up at 5!?

I get that 10-7+2 is 5, sure... but if Net Buy Quantity is (Quantity of Buy order position - Quantity of Sell positions) then why is the exmaple showing 10 - 7 + 2?? Why is it minus 7, which is a sell order, but plus 2, which is also a sell order?

Surely the above example, should be:

10 - 9 | OR | 10 - (7 + 2) = 1

Right?

Then there is the "Net Buy Market Value"

Net Buy Market Value = 10*30,000 + 2*33,000 - 7*32,000 = 142,000

again, information provided:

Net Buy Market Value = Amount of buy orders traded - the number of sell orders traded (quote asset)

I don't get how the example gets to 142,000?

If "Net Buy Market Value" is mount of buy orders traded - the number of sell orders traded then I don't get why the example is indicating "10*30,000 + 2*33,000 - 7*32,000" - Why are we ADDING 2*33,000 - which is a sell order - But we are taking away 7*32,000 - which is also a sell order??

So, once again, shouldn't the "Net Buy Market Value" in the exmaple be:

10 * 30,000 - 2 * 33,000 - 7 * 32,000 = 10,000

OR

10 * 30,000 - (2 * 33,000) - (7*32,000) = 10,000 ?

And Finally the Total Profit / Loss

Total profit/loss = 5*36,000 - 142,000 = 38,000 USDT

With the info / calculation:

Total PNL is calculated as = Net Buy Quantity (of all previous trades)*Index Price - Net Buy Market Value

This time, the calculation would seem to be operating on incorrect numbers from the previous calculations, so if I'm right with the math above, then this would be:

1*36,000 - 10,000 = 26,000 ?

And not the 38,000 that the example indicates?

The information just doesn't make sense to me, and I can't work out if I've just read the information wrong / mis-understood. Or if the example math provided is just wrong and hasn't been checked?

Can someone possibly help me understand this properly?

Edit - Link to the page I'm referencing: https://www.binance.com/en/support/faq/66c9249262904132b40a9566b0c7ac24