Combining Layers by Weighting Attributes

I have several shapefiles that have a list of attributes associated with them. One of the attributes column in each layer is a rank from 1 to 5. I want to combine these into one layer with one attribute field. For instance:

One endangered species layer with an rank from 1 to 5,
One habitat layer with a rank from 1 to 5

So I want to come up with an overall rank for the new layer so if I rank the endangered species layer over habitat the equation for each cell in the new layer would be something like:

2*(rank from endangered species layer)+1*(rank from habitat layer)

How can I do this?

Is there an analysis tool?