Given that a reflection of rectangle PATH across the y-axis forms rectangle SIDE. To map rectangle SIDE back to rectangle PATH without reflecting across the y-axis you'll have to reflect rectangle SIDE across the x-axis, then reflect across y-axis, and then reflect across the x-axis again.
Performing the 3 reflections above will map SIDE back onto PATH
ANSWER:
Reflection of SIDE across the x-axis, then another reflection across the y-axis, and another reflection across the x-axis