why is it charging me 75$ for itunes?

What makes you believe that iTunes is charging your $75? Did you receive an email, or other message? Have you checked your purchases or bank statement to see if it appears there? If so, see this. If you see 'itunes.com/bill' or an unfamiliar charge on your bank, credit card, or debit statement - Apple Support

If it was just an email, see this, as it could be a phishing attempt. This will help identify fraudulent messages and what to do with them. Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

You don't really provide much description of the problem, do you?

See your purchase history in the iTunes Store on a Mac or PC - http://support.apple.com/HT204088 - Does not include purchases made by others under Family Sharing; those have to be checked from their accounts.

If you see ‘itunes.com/bill‘ or an unfamiliar charge on your bank, credit card, or debit statement - https://support.apple.com/HT201382 - "Before you contact Apple to request a refund for a charge you don't recognize"...

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