701 + 2030AD =2730
2730-390-40= 2300

Could anyone please explain why these numbers are used in this particular calculation? I understand the significance of the numbers in relation to Ezekiel (and I think it is amazing that the numbers are used at all) but why, for example, are the 390 and 40 subtracted at the end?
Also, how does it all link to John 2:20 and are there any other prophesies that we can put 2030 into and calculate something interesting?

I almost understand it but there is something that is not clicking fully in my brain. Could anyone explain it in simple terms for me please?