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家庭教師先のガキ、ほんまアホだけど式変形のこと…
→ “That brat from the tutoring job, seriously an idiot when it comes to conjugation...”
家庭教師 katei kyō¹shi = private tutor (noun)
家庭 katei = home / household
教師 kyō¹shi = teacher / instructor
先 saki = place / location (suffix indicating where someone is)
の no = 's / of (possessive particle)
ガキ gaki = brat / kid (slang, often derogatory)
、 = comma (punctuation)
ほんま honma = really / for real (colloquial contraction of 'hontō')
アホ aho = idiot / fool (slang)
だけど dakedo = but / however (conjunction)
式 shiki = formula / pattern (noun)
変形 henkei = conjugation / inflection (verb/noun)
の no = of / about (possessive/genitive particle)
こと koto = thing / matter (noun suffix abstracting a concept)
… = ellipsis (punctuation indicating trailing off or thought)