When finding the Slope from two points , how I check my answer makes sense is?

According to modern science, earth is about 4.5 billion years old and written human history extends back about 10,000 years. suppose the entire history of earth is represented with a 10-meter-long timeline, with the birth of earth on one end and today at the other end.

Which statement best explains why ben uses the width hi to create the arc at j from point k

I'm confused on this could anyone me and show me what i need to do to solve it.