Need two if conditions for a numeric formula

I'm trying to make a numeric formula field that will only calculate a Total Invoice if the Override Points are blank (or zero) AND the Approved checkbox is checked (true).

This part works
If([Project Points Override]=0,
[Project Points]*[Contract Coach - Current Rate],[Project Points Override]*[Contract Coach - Current Rate])

When I try to add the checkbox=true it does not work. I'm sure I'm missing a syntax somewhere here
If([Project Points Override]=0 & [Approved],true],
[Project Points]*[Contract Coach - Current Rate],[Project Points Override]*[Contract Coach - Current Rate])

It says the "=" can't be used on a type number. Any suggestions?

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Dawn Rene
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