I did MTH1010 after doing shit in methods (no shame there). It's rather hard for what it's meant to be. A lot of people failed or so i hear (one friend of mine in the class did though).
Here's the thing, its 2 years of math methods condensed down into a semester (~12 weeks). Just imagine that for a second. In usual uni fashion as well, there's a lecture, you just show up and listen. It's not the same as a classroom. There is a tute with prescribed work after the lecture but its not nearly as helpful or some might say "babying" or easing you through it like in a highschool classroom. Even the VCE equivalent subjects for chemistry, biology, physics, etc all go for two semesters, this is all crammed into a single semester.
I'd respectful disagree with disafear there, mainly because he hasn't done the unit so i'm not sure how much he can really say on it

. It's a bit more full on than methods from VCE, the content is kind of similar but theres definitely not the pace or even really the support.
The thing with scoring 24 in methods and going into a unit like that is that you don't have great math foundations to begin with (i got 1 below his score for the record). Going off my experience, you probably dont understand the fundamental basics or were taught poorly in one way or another. Also going off my own experience, a lot of people just hate or resent mathematics, that was me as well (shock horror). Your friend has to be realistic, if he didn't do all that well in methods, is he really going to magically improve here? I passed the unit (but only just a passing grade) but that was a bad semester for me overall.
You need to communicate all this to your friend and either he needs to work hard at it or potentially fail it. Keep in that commerce (not sure, someone else can comment) is likely to be full of math if methods is the requirement, unless you do something like accounting. If his math skills are poor (thats OK, everyone is good and bad at different things), he isn't likely to have a good time in a math heavy commerce major. He just needs to come to terms with that. For awhile i wanted to do computer science and ignored the fact it was math heavy, i was bad at math and i didn't like math, i somehow mentally pushed it aside but its a
crucial consideration if you want to set yourself up for success.
The prescribed textbook is 100% essential, you need it for the tutes. If you don't do your tute work you don't pass. You should be able to find a second hand copy fairly cheaply.