84 kilometers ... 1 hour
7 kilometers ... x hours = ?
If you would like to know how long does the pigeon take to fly 7 kilometers, you can calculate this using the following steps:
84 * x = 1 * 7
84 * x = 7 /84
x = 7/84
x = 1/12 hour
Result: A pigeon can fly 7 kilometers in 1/12 hour.
Answer:
Wait I just realized, none of them are cubic? for a polynomial to be cubic it needs to be 
It would be (B) because 450+200x4=2620 fence posts
Estimation: about 6,000 (90x70=6300)
Answer (product): 6256
In math the sum means to add