Final answer:
Martha added 16 to both sides of the equation to go from Step 2 (5x - 16 = 81) to Step 3 (5x = 97). This operation is a standard part of the process to isolate the variable when solving linear equations.
Step-by-step explanation:
The student question relates to the process of solving linear equations. Between Step 2 and Step 3 of the equation, Martha specifically performed the operation of adding 16 to both sides. We know this because the equation went from 5x - 16 = 81 in Step 2, to 5x = 97 in Step 3. By adding 16 to both sides of the equation, Martha was able to isolate the variable on one side which is a common step in solving linear equations.
To find the operation conducted between these steps, we observe the change from one step to the next. Since she had 5x - 16 in Step 2 and 5x in Step 3, the -16 must have been eliminated by adding 16 to both sides of the equation. The correct answer to what operation was performed is Option 3: Added 16 to both sides.