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Algebra / Linear equations in one variable Difficulty: Easy

If 2 n over 5, equals 10, what is the value of 2 n, minus 1 ?

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Explanation

Choice B is correct. Multiplying both sides of the given equation by 5 yields 2 n equals 50. Substituting 50 for 2 n in the expression 2 n minus 1 yields 50 minus 1, equals 49.

Alternate approach: Dividing both sides of 2 n equals 50 by 2 yields n equals 25. Evaluating the expression 2 n minus 1 for n equals 25 yields 2 times 25, minus 1, equals 49.

Choice A is incorrect and may result from finding the value of n minus 1 instead of 2 n minus 1. Choice C is incorrect and may result from finding the value of 2 n instead of 2 n minus 1. Choice D is incorrect and may result from finding the value of 4 n minus 1 instead of 2 n minus 1.