 <translate> At six years old, with three times as many dogs as cars, Derek had 90 / 3 = 30 cars. Ten years later, after buying 210 more cars, Derek has 210 + 30 = 240 cars. Since the number of cars is twice as many as the number of dogs, Derek currently has 240 / 2 = 120 dogs. Final answer: 120. <yor> Nígbà tí Derek wà lọ́mọ ọdún mẹ́fà, tó sì jẹ́ pé iye àwọn ajá tó ní pọ̀ ju iye ọkọ̀ ayọ́kẹ́lẹ́ tó ní ní ìlọ́po mẹ́ta lọ, ó ní ọkọ̀ ayọ́kẹ́lẹ́ mẹ́tàléláàádọ́rùn-ún. Ọdún mẹ́wàá lẹ́yìn náà, lẹ́yìn tí Derek ra mọ́kànlélógún [210] ọkọ̀ ayọ́kẹ́lẹ́ mìíràn, ó ní mọ́kànlélógún [210] àti ọgbọ̀n [30] ọkọ̀ ayọ́kẹ́lẹ́ tó jẹ́ òjìlérúgba [240]. Níwọ̀n bó ti jẹ́ pé iye ọkọ̀ ayọ́kẹ́lẹ́ tó wà lọ́wọ́ Derek ju iye àwọn ajá tó wà lọ́wọ́ rẹ̀ lọ ní ìlọ́po méjì ó lé ogún [240/2], ìyẹn sì jẹ́ ọgọ́fà [120] ajá. Ìdáhùn tó péye ni pé: 120. 