Hello Heureka,
yes, this is as they have it also, so I believe this is right...what I struggled with is the centre 30. If you calculated x, it comes out to be 34 and not 30. The equation for maths ends up being x-30. So saying then 34-30, we get 4, which should be math only...however we know that ALL math also take History, so what to do with the 4 then?....cast it outside?...
I do firmly understand the outcome, was just concerned about the fact that x calculated to 34 and not 30, in which case math only would have calculated to 30-30 which is zero...
thank you for helping out to understand this approach..