i think the answer might be 3
According to the information given, the ramp would be 50 feet high. (However, that seems really high. Did you type your problem correctly?)
If you draw a picture, you will see that you can set up a cosine ratio to solve this problem. With a 30 degree angle of depression, the angle we are going to use 60 degrees.
We can set up the following equation:
cos(60) = x / 100
0.5 = x / 100
50 = x
3,322.609847222222 mph. First covert miles to km. This distance is 239227.909 miles. then divide this by the number of hours which is number of days times 24. It took 3 days so it is 72 hours. After diving 239227.909/72 you get your answer of 3,322.609847222222 mph
4/5 is your answer
Hope this helps