 
 <translate> He filled 3 boxes with 15 books each so 3 * 15 = 45 books. From the rest of his house he is donating 45 + 21 + 4 + 18 = 88 books for donation. His collection is 99 books and he is donating 88 books, so that leaves him with 99 - 88 = 11 books. He picks up 12 books to add to his collection of 11 books so he now has 12 + 11 = 23 books.
The final answer: 23. <hau> Ya cika akwatuna 3 da littattafai 15 kowannensu don haka 3 * 15 = littattafai 45. Daga ragowar gidansa yana ba da gudummawar littattafai 45 + 21 + 4 + 18 = 88 don ba da gudummawa. Tarinsa na da littattafai 99 kuma yana ba da littattafai 88, don haka ya bar shi da littattafai 99 - 88 = 11. Ya ɗauki littattafai 12 don ƙarawa zuwa tarin littattafai 11 don haka yanzu yana da littattafai 12 + 11 = 23. Amsar ita ce: 23. 