Fairly simple. You know the length and the area, but you don't know the width. So your equation looks like this: 30 x ? = 180. But to figure out the width, you change the position of the numbers in the equation like this:
180 ÷ 30 = ?. Then you solve. 180 ÷ 30 = 6. If you want to double check your answer, you can plug in your answer to your original equation, 30 x 6 = 180.
