 <translate> Matias sold 7 * 3 = 21 books on Wednesday, as he sold three times more books than on Tuesday. The sales from Wednesday were tripled on Thursday, which means Matias sold then 21 * 3 = 63 books. That means in total Matias sold 7 + 21 + 63 = 91 books during these three days.
The final answer: 91. <yor> 7 * 3 = ìwé 21 ni Matias tà ní Wednesday, nítorí ó ta ìwé tó ju ti Tuesday lọ ní ìlọ́po mẹ́ta. Iye tí wọ́n tà ní Ọjọ́ Àbámẹ́ta ti di ìlọ́po mẹ́ta ní Ọjọ́ Àbámẹ́ta, èyí tó túmọ̀ sí pé Matias ta ìwé 21 * 3 = 63. Ìyẹn túmọ̀ sí pé ìwé tí Matias tà láàárín ọjọ́ mẹ́ta yẹn jẹ́ 7 + 21 + 63 = 91. Ìdáhùn tó gbẹ̀yìn ni pé: 91. 