Answer:
B. Yes, they both mean the same thing. They can also both be represented by the expression y - 6.
Explanation:
Given
Phrase 1: 6 less a number y
Phrase 2: 6 less than a number y
Mathematically,
Phrase 1 can be represented as follows;

Mathematically,
Phrase 2 can be represented as follows;

Since the representation of both phrases are the same, then option B answers the question.