Physics laser slit question?

optical path difference=path from ray2 (right slit )- path from ray 1 (left slit)

D= distance btw the screen and the slits

if you have a bright fringe, the optical path difference = order of the fringe * lambda

since you are on the right side, the optical path difference here equals = - 2 * lambda

which means the light from the left traveled 2*lambda = 1006 nm farther than the light from the right

The distance in their paths is given by dsintheta where d is the distance between slits and theta is the angle between the path of the ray and the screen. The angle isn't needed however because the equation is equal to m lambda, in this case m is 2 and lambda is 503e-9. Therefore light from the left slit travels 1006 nm more than that of the right.