Light is incident on a diffraction grating with 8600 lines/cm, and the pattern is viewed on a screen 2.5m from the grating. The incident light beam consists of two wavelengths, λ1 = 4.6 x 10-7 m and λ2 = 6.8 x 10-7m. Calculate the linear distance between the first-order bright fringes of these two wavelengths on the screen.