 <translate> If they spent two more weeks on their second research expedition than they spent on the first week, they spent 2 + 3 = 5 weeks on the island. In the two expeditions, they stayed on the island for a total of 5 + 3 = 8 weeks. On their third expedition, they spent twice as many weeks as they spent on the second week on the island, which is 2 * 5 = 10 weeks. In all three expeditions, they stayed on the island for 10 + 8 = 18 weeks. Since a week has seven days, they spent 18 * 7 = 126 days on the island.
The answer: 126. <yor> Bí wọ́n bá lo ọ̀sẹ̀ méjì sí i nínú ìrìn àjò ìwádìí wọn kejì ju èyí tí wọ́n lò ní ọ̀sẹ̀ àkọ́kọ́ lọ, wọ́n á lo ọ̀sẹ̀ méjì ààbọ̀ ní erékùṣù náà. Nínú ìrìn àjò méjèèjì, wọ́n lo àpapọ̀ ọ̀sẹ̀ márùn-ún àti mẹ́ta ní erékùṣù náà. Ní ọ̀sẹ̀ kẹta tí wọ́n rìnrìn àjò náà, wọ́n lo ọ̀sẹ̀ méjì lẹ́ẹ̀mejì lórí erékùṣù náà, èyí tó jẹ́ ọ̀sẹ̀ mẹ́wàá. Nínú ìrìn àjò mẹ́tẹ̀ẹ̀ta tí wọ́n rìn, wọ́n lo ọ̀sẹ̀ mẹ́wàá pa pọ̀ mọ́ ọ̀sẹ̀ mẹ́jọ ní erékùṣù náà. Níwọ̀n bó ti jẹ́ pé ọjọ́ méje ló wà nínú ọ̀sẹ̀ kan, ọjọ́ tí wọ́n lò ní erékùṣù náà jẹ́ méjìdínlógún [18] lọ́pọ̀ ìgbà, ìyẹn sì jẹ́ ọjọ́ mẹ́rìndínláàádóje [126]. Ìdáhùn náà ni: 126. 