Answer:
2
Step-by-step explanation:
Answer: Choice A
Step-by-step explanation:
The correct answer is choice A. The equation 81 - a is doing exactly what the question is asking for. It represents 81 minus an unknown number, with the unknown number being shown as a.
Answer:
A
Step-by-step explanation:
Multiply them according to the problem.

As you can see, the only terms in the two equations that can cancel out are
and
.