Double Slit Interference and linear distance

[rachiebaby17]

Homework Statement

In a double-slit interference experiment, the wavelength is 579 nm, the slit separation is 0.12 mm, and the screen is 30.0 cm away from the slits. What is the linear distance between adjacent maxima on the screen? [Hint: Assume the small angle approximation is justified and then check the validity of your assumption once you know the value of the separation between adjacent maxima.]

Homework Equations

where
λ is the wavelength of the light,
d is the separation of the slits, the distance between A and B in the diagram to the right
n is the order of maximum observed (central maximum is n=0),
x is the distance between the bands of light and the central maximum (also called fringe distance), and
L is the distance from the slits to the screen centerpoint

The Attempt at a Solution

Again I'm completely lost, some hints on how to start would be great

 

[rl.bhat]

Write down the equation for xn, linear distance of the nth bright fringe from central maximum and similarly for x(n-1) of (n-1)th bright fringe. The difference between these will be the required result.