In a Young's double slit experiment a screen is placed 75.0 cm from two slits spaced 0.450 mm apart. (a) If the slits are illuminated with coherent light of wavelength 500 nm, what is the dis- tance between the first and third-order dark fringes? (b) What is the spacing between the first- order bright fringe and the second order dark fringe? (c) How many total bright fringes are seen on the screen?