Ooh very interesting question!
Hmm the only thing I could think of...
...was different bases, until I saw you'd put it in words rather than 7 equalling 12
If it were base twelve, 1212 would equal fourteen, in which case 7 is indeed half of 14.
I have heard of problems like "when does 11 + 2 = 1" in which case, answer is on a clock but I don't think that works for this one here. This is an interesting problem
And woah @JonnyGamer, your friend's worksheet looks really fun!! So many to choose from... one that caught my eye was the second one under the heading 'Algebra II & Geometry'