ANSWER
The length of PR is
[tex]9 \: \: units[/tex]
EXPLANATION
The two triangles are similar. Therefore their corresponding sides are proportional.
[tex] \frac{|PR|}{ |XZ |} = \frac{|PQ|}{|XY|} [/tex]
We substitute the length of the known sides to obtain,
[tex] \frac{|PR|}{ 27} = \frac{7}{21} [/tex]
We now multiply both sides by 27 to get,
[tex] |PR| = \frac{7}{21} \times 27[/tex]
This simplifies to
[tex] |PR| = \frac{1}{3} \times 27[/tex]
This gives us,
[tex] |PR| = 9 \: units[/tex]
The correct answer is C
