Been a while since i used Excel formula's. Looking for help if possible with the below please guys.

Formula if a straight forward average formula, the issue is I want the formula to show a 0 or blank cell if the formula is not able to be applied due to there being data other than number in the cells. So the cell can contain a number or NR or N/R.

So the formula I have that isn't working is:
=AVERAGE(E7:N7), IF(E:G,"N/R"or"HR","")

Any ideas?