* The vehicle's data plate: Located usually on the driver's side door jamb or under the hood. This *might* list the axle ratio, but it's not guaranteed.
* The differential tag: This tag is usually located on the differential housing itself. It will have the ratio stamped on it.
* The owner's manual (if available): This could list the specifications for the vehicle.
Without checking one of these sources, it's impossible to definitively state the gear ratio.