(1) Find the greatest common divisor of 24 and 32. Is 8, at this time 1 class has 3 groups, and class 2 has 4 groups.

(2) Find the least common multiple of 12 and 15. Yes 180.

(3) Most pens are used, and the scores are the same, with red ink 2/ 15, pen 5/ 15 and manuscript paper 3/ 15. The most pens are known.

(4) Xiaogang's composition time is 20 minutes, which is longer than Xiaohong's, so Xiaogang is far from the library.