Boris donates 24 / 4 = <<24/4=6>>6 books
Then Boris has a total of 24 - 6 = <<24-6=18>>18 books
Cameron donates 30 / 3 = <<30/3=10>>10 books
Then Cameron has a total of 30 - 10 = <<30-10=20>>20 books
Altogether, Boris and Cameron have 18 + 20 = <<18+20=38>>38 books
#### 38