Answer:
3cm
Step-by-step explanation:
A parallelogram is quadrilateral that has two pairs of parallel sides. The opposite sides equal in length
Area of a parallelogram = base x height
18cm² = 6cm x height
height = 18cm² / 6cm = 3cm
Step-by-step explanation:

From the diagram associated with this question it can be seen that the first bounce was 1 units high, thus the second bounce is 1 / 2 = 0.5 units high and the third bounce is 0.5 / 2 = 0.25 = 1/4 units high.
Given that B represents the second bounce and C represents the first bounce, the <span>fractions in hundredths that should be written at points B is 0.50 while at point C is 0.25</span>
An inequality can be formed by simply translating the problem statement to numerical expressions.
From the problem we know that

added with

hours should be equal or greater than

(helpful insight from the keyword "at least"). Therefore, it's inequality would look like:

(>= is used instead of ≥ for constraints in formatting)
The inequality above best models the situation.
Triangle Area = .5 * base * height
48 = .5 * (x +4) * x
48 = (.5x + 2) * x
48 = .5x^2 + 2x
.5x^2 + 2x -48 = 0
x = 8
base = 12