A textbook store sold a combined total of 308 physics and biology textbooks in a week. The number of physics textbooks sold was three times the number of biology textbooks sold. How many textbooks of each type were sold?
Let X be the number of biology textbooks.
The number of physics textbooks is 3*X.
The total number of textbooks is X + 3*X = 308.
4*X = 308
X = <<77=77>>77 books
The number of physics textbooks is 3*77 = <<3*77=231>>231 books. Answer: \boxed{231, 77}.