x+2x+ 12+x-20= 1000
X=252 copies
There are 252-20=232 literary and artistic books.
There are 252×2+ 12=5 16 scientific and technological books.
I hope I can help you. @ Math Tutoring Group # I wish you progress in your study. Please ask questions if you don't understand, and adopt them in time if you understand! (*^__^*)