Here's an update on my original post: I've just been to see the maths teacher this morning and explained that DCs couldn't do all of the homework as we were all ill and also because they couldn't even begin to understand how to do the algebra bits.
He looked surprised and said that in this middle Maths group, there were 3 levels and he'd given my sons the easiest level homework!
They'd already done lots of sums like this last term and shouldn't have had any problems!
I then confessed that even I couldn't figure it out, as it's 32 yrs and more since I did this kind of thing and I added that I wasn't doing this level of Maths at age 9 anyway.
He said that this was the standard level for Yr 5 in this school and reiterated that my DCs had been given the lowest level of this!
I felt so embarassed! He said he'd chat with them about the difficulties they'd had and give them some even easier examples of these sums to take home - ie the year below them - but wouldn't tell them it was Yr 4 stuff. I asked him if he could give me a sheet telling me exactly how to approach these algebraic sums so that I could then support my sons and felt I had to apologise again for not being able to do them.
He was very nice about it but clearly surprised they'd had any difficulty at all. He said that what they're trying to get the children to do is think around maths and reflect on how to approach problems, as well as getting the answers right, of course and that it was pointless just to give them a standard set of sums that anyone could do easily. He said that they needed to fail and accept they'd failed and then re-apply themselves and 'think outside the box' because in real life and at higher mtahs levels, you have to do this - not just stick to a standard formula.
I told him point blank that it was unlikely I'd be able to help my sons in maths as clearly the level for a standard 9 yr old - in this type of school - is beyond my 47 yr old skills! All this was in a friendly and jokey manner.
However, I'm left reeling. Given the feedback here and also the two other RL friends I approached with children in the same Maths group - the consensus of opinion was that these were rather weird and tricky sums and most probably beyond a 9 yr old' s ability.
But the teacher was v matter of fact about it and clearly DCs will need to get to this level quickly and beyond, as they have exams coming up in February. At that stage, they may at the v least be put down into the bottom group - which although not necessarily a bad thing, will crash their confidence levels. Their maths group has 26 in the class and one teacher. The bottom group has 20 in the class and f/t TA for the group.
It's also the stage at which the school decides whether or not to support your children's entry into the seniors for Yr 7 (they recently did away with the actual entrance exam for those already at the prep.). If they don't support you, then you have to get your DCs to do the external exam and having not got the support of the prep. feeder for the application, it's highly unlikely a child will get in.
So I'm in a state of high anxiety now and wondering how on earth I'll get time to re-educate myself in maths and then teach DCs daily in those skills, whilst also running a f/t business single-handedly and a home....