I'm a bit confused as to where to put this, because as far as i know there's no section for "Equations"

But i've been reading through an introduction to Equations! That's the booklet i have started studying and it has: y + 2 and 5f - 1 are expressions. y and f are called variables. I know all that!

But maybe it's just the case that i've just come off my school holidays, and i'm a bit slow! But i can really remember how to do the following! well i don't really have to do it, i'm not mean't to! Right now it's just stating fact, but when i read i like to be ableto understand what their talking about: y + 2 = 11, and 5f - 1 = 14! i do understand that 5 - 1 is 4! but if it was to live upto the result of 14! it all depends on what the "f" stands for! so in this case would the f stand for 10? But how would y + 2 equal 11??