The expressions are not equivalent.
Work Step by Step
If there is something in the numerator and denominator of a fraction, we can cancel that thing out of the fraction. Although this step may be slightly new to us, we have used this thought process before. Recall, when we were simplifying fractions earlier in the book, we could simplify 2/2 to 1 because the 2's canceled out to get 1. Similarly, in the expression 81xy/3x, we cancel out 3x/3x to get 27y. 27y does not equal 9xy, so the expressions are not equivalent.