Final answer:
To find the missing base of the parallelogram, we need more information about the height.
Step-by-step explanation:
To find the missing base of the parallelogram, we need to use the formula for the area of a parallelogram, which is base times height. We are given the area (20 units squared) and the height (which is not provided). Let's assume the missing base is b. So, the formula becomes:
20 = b x height
Since we don't have the value for the height, we can't solve for b. More information is needed to find the missing base.