Karina read a total of 20 2/4 pages in her science and social studies books combined. She read 12 3/4 pages in her science book. To find out how many pages she read in her social studies book, we need to subtract the number of pages she read in her science book from the total number of pages she read in both books. Here's how to do it step-by-step: 1. Convert the mixed numbers to improper fractions: 20 2/4 = (20 * 4 + 2)/4 = 82/4 12 3/4 = (12 * 4 + 3)/4 = 51/4 2. Subtract the improper fractions: 82/4 - 51/4 = (82 - 51)/4 = 31/4 3. Convert the improper fraction back to a mixed number: 31/4 = 7 3/4 So, Karina read 7 3/4 pages in her social studies book. Answer: 7 3/4 pages.