True Altitude example questions

[MadMadMike]

Getting ready for ATPL Nav and not 100% confident on calculating true alt. Think I have it down but not many example questions in the ATF notes to make sure I definitely have it squared away.

Anyone feel like writing a few out so I can have a go at a few more. Be very much appreciated. Thanks :ok:

[goldeneagle]

Hey mate, try OAT minus 15, divide by 300, then multiply by height above GROUND level.