ExplanationThe sequence \(a_n = a_{n - 1} - 7\) can be read as “to get any term in sequence a, subtract 7 from the previous term.” The problem provides the 7th term; plug the term into the function in order to determine the pattern.

Note that Quantity A asks for the value of a1, so try to find the 6th term:

\(7 = a_6 - 7\)

\(a_6 = 14\)

In other words, each previous term will be 7 greater than the subsequent term. Therefore, \(a_7 = 7\), \(a_6 = 14\), \(a_5 = 21\), and so on.

The term \(a_1\), then, is greater than the starting point, 7, and must also be greater than the negative value in Quantity B. Quantity A is greater. Note that the value in Quantity B is the result of incorrectly subtracting 7 six times, rather than adding it.

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Sandy

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