9 / 10-1 / 15-2 / 15

9 / 10-1 / 15-2 / 15

9/10 - 1/15 -2/15=9/10-（1/15 + 2/15）=9/10- 3/15=9/10-1/5=（9-3）/10=3/5

The number of class 6 (1) is 10 / 11 of that of class 6 (2). The number of class 6 (1) is several percent more than that of class 6 (2)

How many percent more people are there in class 6 (2) than in class 6 (1)? 10 / 11 = 10:11, (11-10) / 10 = 0.1 = 10%, a: Class 6 (2) is 10% more than in class 6 (1)

The number of people in class 6 (1) is 11 / 10 of that in class 6 (2). The number of people in class 6 (1) is several percent more than that in class 6 (2)

There are 100 people in class 62 and 110 people in class 61
It is easy to know that the number of class 6 (1) is more than that of class 6 (2) (110-100) / 100 = 10%

11 out of 15 + 4 out of 15 / (1 and 4 out of 9-2 out of 3 * 5 out of 6)

11 out of 15 + 4 out of 15 / (1 and 4 out of 9-2 out of 3 * 5 out of 6)
=11 / 15 + 4 / 15 / (13 / 9-5 / 9)
=11 out of 15 + 4 out of 15 / 8 out of 9
=11 out of 15 + 4 out of 15 / 8 out of 9
=11 out of 15 + 3 out of 10
=31 out of 30