Well, i'm not anywhere near intermediate or expert, but a mch shorter piece of code would be...
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textbox4.text = val(textbox1.text) - val(textbox2.text) + val(textbox3.text)

textbox7.text = val(textbox4.text) - val(textbox5.text) + val(textbox6.text)

textbox10.text = val(textbox7.text) - val(textbox8.text) + val(textbox9.text)

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u can make a button and double click it, then add that code.

i realize this isn't an advanced way of doing things, but this question is coming from a beginner who probably wants to learn just one thing at a time.

Ideally, indeed the output should be in labels, and the input should be in numeric updowns

hope this helps