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Answer: thickness=3.15*10^(-4) meters

To solve this, you can use the equation:

Volume=area*thickness

thickness=volume/area

thickness=(3.78*10^-3)/(12.0)

thickness=3.15*10^(-4) meters

To help you better understand the issue, you can assume that thickness is in the unit of 'meters'. You are given the volume in 'meters^3' and area in 'meters^2'. To get an answer in 'meters', you can divide the volume by the area, and the 'meters^2' will cancel out, leaving you with 'meters'.

Please let me know if you need any clarification. I'm always happy to answer your questions.