Answer:
It is given that,
The garden is in the shape of a trapezoid
From the given figure,
The length of the bottom of the trapezoid,


The length of the bottom of the trapezoid is 20 feet
The length of the top of the trapezoid is,

The length of the two parallel sides of the trapezoid are 20 feet and 12 feet.
To find the height of the trapezoid
Height of the trapezoid is,

Height of the trapezoid is 6
To find the area of the trapezoid
we know that,
Area of the trapezoid is

where a and b are the paralell sides of the trapezoid and h is the height of the trapezoid.
Substitute the values we get,
Area of the trapezoid is


Area of the trapezoid is 96 feet.