The first question is that there are 3/8 fewer science and technology books than story books, so the proportion of science and technology books in story books is 5/8, so 400 divided by 5/8 is 640 story books.

The second question, we have done 3/5, so there are still 2/5 miles, that is, 245 kilometers. So divide 245 by 2/5 to get1112.5km. ..

The third question is similar to the second. You did the right thing.

Fourth. Five questions are also right. 3. Right

4. Right

5. Right 1. Two disjoint lines are called parallel lines. (Wrong) It should be correct that two lines that do not intersect in the same plane are called parallel lines. 2. The distance between two parallel lines is equal. (right) 3. On the same plane.