Final answer:
To represent the length of the original piece of lumber after 12 centimeters have been cut, we use the equation: Original length = c + 12.
Step-by-step explanation:
To represent the length of the original piece of lumber, we can use the equation:
Original length = c + 12
Here, c represents the length of the lumber after 12 centimeters have been cut from it. So, by adding 12 to c, we get the original length of the lumber.
For example, if c = 20, then the original length would be:
Original length = 20 + 12 = 32
Therefore, the correct answer is A. c.