Can you pls explain why too

Answer: C / 100 units^2
Step-by-step explanation:
The equation to calculate the area of a rhombus is
[tex]Area = \frac{ab}{2}[/tex]
In the picture, you are given a & b.
a equals the entire vertical line. So 5 + 5 = 10. 10 is a
b equals the entire horizontal line. So 10 + 10 = 20. 20 is b.
According to the equation you multiply a times b.
[tex]Area = \frac{(10)(20)}{2}[/tex] 10 x 20 = 200
200 divided by 2 equals 100
so the areas = 100