To do Alt + M P on Mac in Excel, download and install Accelerator Keys, then press Option, followed by M, P.
Command: Trace Precedents
This is how to do Alt + M P on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + M P trace Precedents shows arrows from cells that feed into the selected formula. This helps you understand where a formula gets its input values.