Ascale drawing of a movie screen is 21 inches long and 9 inches tall. the actual screen is 30 feet tall. what is the scale of the drawing?

Okay so first you need to fix the numbers; I put both sides into feet so the equation would look like this: 1.75/.75=x/30. now you just cross multiply and divide: (30x.75)/1.75. that means x=12.8571429... (13). from there you divide: 1.75/.75=2.3 and 30/13=2.3. that means the scale is x2.3!
I hope that makes sense.