Answer:
She did not divide 28 by 4
Explanation:
Here, the given expression is,
4x = 28,
The step involve in solving this expression are as follows,
Step 1 :

Step 2 :

Step 3 :

Thus, by the above steps it is clear that she should divide both sides by 4 for isolating x on left side,
Hence, the required statement that best explains her mistake in steps 2 is,
'She did not divide 28 by 4'