Answer:
Amy's garden has the greater area by 4 square feet
Step-by-step explanation:
we know that
The perimeter of a rectangle is given by the formula

step 1
Rectangular garden of Amy
we have

substitute in the formula of perimeter

solve for W
simplify

Find the area
Remember that the area is equal to

step 2
Rectangular garden of Zach
we have

substitute in the formula of perimeter

solve for W
simplify

Find the area
Remember that the area is equal to

step 3
Find the difference of the areas

therefore
Amy's garden has the greater area by 4 square feet