Automatically resize an object by a percentage when a particular object style is applied to it

I work for an education company, and we deal with a good number of fractions when writing our publications. We currently use MathType to generate the fractions, which saves each fraction as a separate .eps file so we can place them into InDesign.

However, the fractions generated by MathType are 100% of the font we set within MathType, and we'd like for them to be scaled down a bit...say to 85% of the "base" font size.

Is there any way we can have InDesign scale down these fractions by a percentage?

Not all of the equations brought in by MathType are fractions, so we'd need a way to target just the fractions. One idea I had while writing this was to tag each of the fractions with the object style of "fraction," and then use a script to sniff out all of these and change the size by 85%. Any direction on where to go for a method like this (or another that might work) is greatly appreciated!

Thanks