1. The problem statement, all variables and given/known data Light passing through a two-slit grating makes a pattern on a screen located 500 mm away. In this pattern, the fifth-order dark fringe is 45.0 mm from the central bright fringe. How far from the central bright fringe is the third-order bright fringe? 2. Relevant equations This is what I'm looking for help on. 3. The attempt at a solution I'm not even sure which equations to use to solve this. Any ideas?