Solution:
2. Barlow School: (4 / 9) * 873 = 388 of the students are boys.
873-388 = 485 of the students are girls.
The b(boy) to g(girl) ratio at Barlow School is 388b:485g
1. Willow School: (2 / 3) * 630 = 420 of the students are girls.
630-420 = 210 of the students are boys.
The b(boy) to g(girl) ratio at Willow School is 420g:210b
3. 388 - 210 = 178
Answer: Barlow School has the greater number of boys by 178 students.