Create a formula using multiple if and functions?

Hi, I am trying to work out body fat percentages for subjects in my database for a research project.

The formula is fiendish and I have been trying for weeks to do it in excel with no success - I first tried by combining multiple if(and) formulas but couldnt get it right, and then tried to construct a VLOOKUP table. Please help!

So, the formula is this:

First, I need to work out Body Density:

BODY DENSITY = C-[M(LOG10 SUM OF ALL FOUR SKINFOLDS)]

Where, C & M are constants derived from logistic regression curves from population studies - thus vary according to *** and age. Thus:

MALE 17-19 YRS 20-29 YRS 30-39 YRS 40-49 YRS 50 + YRS
C 1.1620 1.1631 1.1422 1.1620 1.1715
M 0.0630 0.0632 0.0544 0.0700 0.0779

FEMALE 16-19 YRS 20-29 YRS 30-39 YRS 40-49 YRS 50 + YRS
C 1.1549 1.1599 1.1423 1.1333 1.1339
M 0.0678 0.0717 0.0632 0.0612 0.0645

And then, to work out %Fat - need to do this formula:

THE SIRI EQUATION
Fat % = [(495 / BD) - 4.5] * 100

I have tried nesting multiple "if and" functions as well as constructing a VLOOKUP table with no success.

If anyone can help I will be eternally grateful!

Thanks,
Molly

Welcome to the forum, molly.

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Thanks.