Final answer:
The equation a + 6b = d is solved for a by subtracting 6b from both sides, resulting in the answer a = d - 6b.
Step-by-step explanation:
To solve for a in the equation a + 6b = d, you must isolate the variable a on one side of the equation. Start by subtracting 6b from both sides of the equation, which yields a = d - 6b. This manipulation gives you the solution in which the variable you are solving for, a, is on one side of the equals sign, and the entire expression d - 6b is on the other side. Therefore, the correct answer is B) a = d - 6b.