Please show your work and box answers

4. (25 points) White light is incident on a diffraction grating with 550 lines / mm. The interference pattern is projected onto a screen 2 meters away from the grating. a. (15 points) How far apart is the lst order red (A = 700 nm) bright fringe from the lst order violet (A = 400 nm) bright fringe? b. (10 points) If the distance to the screen is cut in half, what is the new distance between the lst order red and violet bright fringes