Help i have a question about LCD

how do you find x in 1/x-1/y=-1/z

so confused. please explain!

http://www.flickr.com/photos/dwread/6496…

First you have to separate x from all the other variables:
1/x= -1/z + 1/y

Then, just simplify:
1/x = -y/(yz) + z/(yz)
1/x= (z-y)/(yz)
x= (yz)/(z-y)