Add Two Numbers And Divide The Result By Another Number

I have a simple formula that adds two numbers and divide the result by another number

K1: SUM(E1,F1) / H1
K2: SUM(E2,F2) / H2
K3: SUM(E3,F3) / H3
K4: SUM(E4,F4) / H4
K5: SUM(E5,F5) / H5

etc, etc

and then I average the results

AVERAGE(K1:K5)

etc, etc

When H1, H2, H3, etc is 0, it generates a #DIV/0! (since you cannot divide by 0)

I want a formula that I everytime a H1, H2, H3, etc is 0, I want to set it to a specific number H1, H2, H3, etc to 15.00

For example:

IF (H1 = 0, 15.00, sum(E1,F1) / H1)

If the number provided (H1) is 0, set it to 15.00, otherwise add the two numbers (E1, F1), and divide this result by the number provided (H1)

But this is where the problem is:

In every single cell that I have NOT yet provided information, it treats the BLANK cells as if it was 0, and has set every single cell to 15.00.