“Who would draw a picture to divide 2/3 by 3/4?” asked Marina Ratner, a professor emerita of mathematics at the University of California at Berkeley, in a recent Wall Street Journal opinion piece.

\(\frac{{{a^2}b}}{{a{b^2}}} = \frac{{a \times a \times b}}{{a \times b \times b}}\) Since a and b are both factors, cancel this fraction by dividing by both a and b ...