Answer:
Area denometer and square expression
Ben's latest journey will take him from Tokyo to San Francisco, and is set to last for five months. That's 5,500 miles worth of swimming, the first-ever attempt by someone to cross the Pacific in this way. Ben will be swimming eight hours<span> a day at the average speed of two to two and a half knots per hour</span>
By rename do you mean turn into an improper fraction?
if so, it is because without turning it into an improper fraction, you cannot subtract 3/4 from 1/4 because you would get a negative answer and that would be incorrect
Physical, Political, and Special purpose
Each system is unique, yet each interacts with the others.