The school band is comprised of middle school and high school students but it always has the same exact capacity. last year the ratio of the number if middle school students to the number of the high school students was 1: 8. however this year the ratio of the number of middle school students to the number of high school students changed to 2: 7 if there are 18 middle school students in the band of this year how many fewer high school students are in the band this year compared to last year