## When Xiao Hua looks at a book, the ratio of what he has read to the total number of pages is 1:3. If he looks at another 15 pages, he will see 12 pages of the complete book?

A: there are 60 pages in this book

Wang Ming read a story book. For the first time, he read 3 / 4 of the whole book. The next day, he read 7 / 20 of the whole book. The next day, he read 15 more pages than the first day. How many pages does the story book have?

15 ／ (7 / 20-1 / 4) = 15 ／ 2 / 20 = 15 × 20 / 2 = 150 pages