Two trains leave the station at the same time, one heading east and the other west. the eastbound train travels 14 miles per hour faster than the westbound train. if the two trains are 640 miles apart after 4 hours, what is the rate of the eastbound train?

4[X+(X-20)]=640
4[2X-20]=640
8X-80=640
8X=640+80
8X=720
X=720/8
X=90 MPH FOR THE EAST BOUND TRAIN
90-20=70 MPH FOR THE WEST BOUND TRAIN
PROOF:
4[90+70]=640
4*160=640
640=640

In all honesty, there really is no “work” per say to show. mainly it’s just using the process of elimination. the question is asking which domain(s) would be the most appropriate for the function c(n). n is the number of observed vehicles so right away, 1, 2, and 3 can be eliminated.why? 1, 2 start in the negatives and therefore it is impossible to observe negative cars. so, #4 would be the best answer to the given problem.

The answer is, the streetlight is 18 inches tall.