1. The problem statement, all variables and given/known data A 10-cd point source lamp and a 70-cd point source lamp cast equal intensities on a wall. If the 10-cd lamp is 8.0 m from the wall, how far from the wall is the 70-cd lamp? 2. Relevant equations I'm not sure what the equation for a candela is. 3. The attempt at a solution Can't attempt it without knowing an equation. That's the only information given, and I don't know how to form an equation.