Answer:
Step 3
Step-by-step explanation:
Given

Required:
Determine the first step where she made mistake
Her Step 1:
--- This is correct because she solved the bracket first
Her Step 2:
--- This is correct because she solved 3^2 as 9
Her Step 3:
--- This is incorrect because 23 * 4 is not equivalent to 9 * 4
Hence, her first mistake is in step 3.
The correct expression would have been

Then

Answer:
2
Step-by-step explanation:
13x2=26
14x3=42
Greatest common Factor of 26 and 42 is 2