I don’t know how to explain this to you step by step but when it comes to questions like this try to think more “logically” (if that makes sense) especially if you’re not familiar with the topic, like me. Think about it, if it was the first one the line on the graph would be above the middle line (its addition plus its greater than y so that wouldn’t be correct). Now the second one is subtraction but its less than y and everything thats coloured goes up not down so it has to be greater than y. C is not the correct answer because its a regular equation and thats not what the question wants plus its the only question out of the the 4 answers which is completely the odd one out so you can just cancel that out. Mow we come to the last answer which is the correct answer because it follows all the right “points” I mentioned earlier. I hope this makes sense to you, sorry I couldn’t explain it better!
