ANSWER
(54/j)²
EXPLANATION
We have to translate this verbal phrase into an algebraic expression. An algebraic expression is a combination of variables, numbers, and arithmetic operations. For example, the expression (x² + 2) is an algebraic expression.
In this phrase, we have "the square of ...", so we will have an expression in the form (...)².
Then, the square is of a quotient, between 54 and j, where 54 is the numerator and j is the denominator.
Hence, the algebraic expression is (54/j)².