Answer: 
Step-by-step explanation:
Move all terms to one side
Simplify
Split the second term
Factor out common terms in the first two terms, then in the last two terms.
Factor out the common term

Think of factor pairs. She could buy 1 pair for $54, 54 pairs for $1, 2 pairs for $27, 27 pairs for $2, 3 pairs for $18, 18 for $3, 6 pairs for $9, or 9 pairs for $6