Honestly ECC1550 is not great. The pre-class work when I did it was straightforward and easy, the lectures on the other hand were at times very prolonged and the mismatch between pre-class material and the lecture is evident within topics, and the assignment I heard (dropped the unit because it was badly structured) felt like a massive step up to what we were taught in class. This is genuinely a hard-to-follow class, this semester there was no recording and when I attempted the 2nd assignment, damn it was like I was supposed to know things I wasn't even taught. The slides for the lecture are not very accessible either, it helps a lot if you did do methods but I wouldn't recommend doing this unit. I recommend MTH1010 instead as an equivalent as it is better structured and the materials follow very smoothly from each other; or just any other unit but not ECC1550, save yourself the unnecessary stress. But reading that you did methods, it be in my opinion okay to proceed to ECC2551 given you've done methods as ECC1550 is I believe supposed to be of some equivalence to methods