1. The problem states that the surface area (S.A.) is 7.5. We need to understand what shape or formula this surface area corresponds to, but since it is not specified, let's assume it is a general surface area value. 2. Surface area formulas depend on the shape. For example, for a cube, S.A. = 6a^2, where $a$ is the side length. 3. If you want to find a dimension from the surface area, you need the formula for the specific shape. 4. Since the problem only gives S.A. = 7.5 without further context, no further calculation can be done. 5. Please provide the shape or additional information to proceed with calculations.