The maximum grade allowed between two stations in a rapid-transit rail system is 3.5%. between station a and station b, which are 310 ft apart, the tracks rise 9 1/2 ft. what is the grade of the tracks between these two stations? round to the nearest tenth of a percent. does this grade meet the rapid-transit rail standards?

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this

1) 2/5

2) zero=0/1

3) zero=0/2

4) -4/5

5) undefined=3/0