In which of the following systems can elimination be used to eliminate a variable by performing addition only? 2x – y = 8 x – 2y = 9 2x – y = 8 x – 2y = 9 2x – 4y = –2 5x – 2y = –2 2x + y = 8 3x – y = 4

The answer would be true!

It depends on the subject for me. some exams are easier than others so i usually go through it and answer questions i know based on my general knowledge, then double check after. going through the lesson can a lot  because the exams can be  very lesson-specific, but sometimes they are ridiculously long so a lot of people don't take the time. i did find that, when i went through the lessons, i was making 100's on my exams vs strictly using + the internet and  i make 90's.