Rosamaria is correct answered.
Since, Sam is missing power , then he is wrong answered.
Rosamaria is correct answer.
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
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, then he is wrong answered. ![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")