Final answer:
When substituting a = 6 into the expression 7(a + 2), the equivalent expression is 7(6) which simplifies to 56. Option (a) is the correct answer.
Step-by-step explanation:
The question asks which expression is equivalent to 7(a + 2) given that a = 6. To find the equivalent expression, substitute the value of a into the equation:
7(a + 2) = 7(6 + 2) = 7(8)
Now, multiply 7 by 8 to get the simplified result.
7(8) = 56
Therefore, the equivalent expression, when a = 6, is 7(6) which corresponds to option (a).