Conditional divide (divide if)

[eendje]

B C D
10 1 5
8 0 6
4 1 4

This is a short version of my sheet. Column C only contains 1 or 0. Column B and D all sorts of numeric values.

For each cell in column A I want to check if the corresponding cell in column C contains a 1 and if so, I want it to divide the corresponding cell in column B with that one of column D. If the value in column C is 0, it should return 0

So in the example above, Column A would have the values 2 (10/5), 0 (since C=0) and 1 (4/4).

To be more accurate, I want to use this formula inside another formula, something like:
=1-$A2+$A2*(B4/D4+B6/D6+...+...for all where column C has value of 1)

Can anyone assist me with this please? I looked a bunch but couldn't find the solution.

 

[eendje]

Actually, the formula still does not exactly do what I need it to (my bad, I did not explain the whole thing, sorry).

I am using circular reference formula and have iterative calculations enabled. (allowing circular references is a must for what I want).

Therefor, to keep my cirular references intact, the formula should state that where ever the corresponding value in column C = 0, it should NOT do the dividing (cuz it could result in deviding by 0 where my whole circular reference system collapses).

Anyway to achieve this? (pardon for the bad spelling)

 

[pgc01]

... where ever the corresponding value in column C = 0, it should NOT do the dividing ...

In that case, try:

=SUM(IF(C1:C3,B1:B3/D1:D3))

This is an array formula, you must confirm it with CTRL-SHIFT-ENTER