Equational

So I’ve been paid! Finally! That said, given that this was for two invoices of x×y where x is my hours and y in my hourly rate, how come:

2x(x×y > p after t has been deducted

where p is my net pay and t is my tax

Not that I’m complaining, mind you, just curious into the ways of tax and national insurance contributions. And they say tax doesn’t have to be taxing?!!!