Answer: 2 x 2 x 2 x 2 x 2 x 5 x 5
Explanation:
We start with the string 2 x 2 x 2 x 2 x 5 x 5
Then we tack on a "2 x" up front, or at the very left, so that we double the result. This is because the jump from 400 to 800 is "times 2".
So we go from 2 x 2 x 2 x 2 x 5 x 5 to 2 x 2 x 2 x 2 x 2 x 5 x 5
We can condense this into 
Translating into a mathematical equation:
n + n^2 = 72
Rewriting, n^2 + n - 72 = 0
Factoring, (n+9)(n-8) = 0
Solving for n: n = -9 or n = 8
You must check both answers before accepting one, the other or both.
Example: suppose we check out n = 8. Then 8 + 8^2 = 72 is true, and n = 8 is a solution. Is n = -9 a solution? Try it.
Two figures are known as similar figures if there the corresponding angles are equal and the corresponding sider is in ratio. The value of x is 10. Thus, the correct option is B.
<h3>What are Similar Figures?</h3>
Two figures are known as similar figures if there the corresponding angles are equal and the corresponding sider is in ratio. It is denoted by the symbol "~".
Since the two prisms are similar, their sides will be in a common ratio. The value of the common ratio will be,
Common ratio = 4/2 = 5/2.5 = 3/1.5 = 2
Since the common ratio of every side is equal to 2, the value of x can be written as,
Common Ratio = 20/x = 2
20/x = 2
x = 10
Hence, the value of x is 10. Thus, the correct option is B.
Learn more about Similar Figures:
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