Can some kind soul enlighten me

Does the GCSE syllabus--- edexcelrequire knowledge of simultaneous equations for 2 variables or does it have 3 variables as well?

Unable to find out myself and child is stuggling with it

https://qualifications.pearson.com/en/qualifications/edexcel-gcses/mathematics-2015.html

I could only see reference to two variables in the spec. I would check with DS2, but he's out. And DD has probably obliterated all memory of Maths GCSE by now (even though she did get a 7) .

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Outside of a dog, a book is a man's best friend. Inside of a dog it's too dark to read.Groucho Marx

DD only did 2 variable SEs to gcse and she sat last summer.

Thankyou that's very helpful
I A my not sure why students have been given this in hw-- probably challenge question