1. Line 3 is the first error. In order to get rid of the 25, you add it to both sides, not subtract. So, your answer is B.
2. Line 1 because it says in the question "4
less than a number" and the equation adds 4, instead of subtracting. Your answer is A.
3. Line 4. To get rid of the 6 in front of 6x, you have to divide by it, but instead they multiply. So, your answer is C.
4. To solve this, you will use the distributive property first:

Turns into:

Get rid of the 12:

Divide by 4:

Your answer is B.
5. You have to set it up:

Just solve for x:

Multiply both sides by 3 to isolate x:

Your answer is B.
Hope this helps, if any step doesn't make sense, feel free to tell me!