If only the Guide is printed, factory A will print 900*5/3= 1500, and factory B will print 1200*7/4=2 100. If only "teaching materials" are printed, factory A will print 900*5/2=2250, and factory B will print 10.

Factory B only prints 2 100 copies of the guide for the whole month, while factory A prints textbooks.

Printing the Guide requires 3/5 of the printing time of 150 textbooks, and then printing 60 textbooks of the Guide.