The ratio of 11k boys to 9k girls. (We use k as a variable because in ratio question the numbers are the divisors of the original number). We have to subtract 9 from 11, we find 2. Since the original numbers of the boys and girls can be divided by 11 and 9, we can understand that by dividing 124 to 2 we will find the value of k. k = 62 . Then we do the multiplication. 62 . 11 = 682, 62 . 9 = 558. Then we add them to find the TOTAL number of students. 682 + 558 = 1240