Final answer:
The compound inequality for the area of the rectangle in terms of x is 20 ≤ 4x ≤ 80.
Step-by-step explanation:
The area of a rectangle is found by multiplying its length and width. In this case, the length is given as 6x and the width is given as 2/3. To find the compound inequality for the area, we need to multiply the length and width and compare it to the given inequality 20 ≤ a ≤ 80.
The area of the rectangle is given by a = (6x)(2/3) = 4x. So, the compound inequality for the area in terms of x is 20 ≤ 4x ≤ 80.