A textbook store sold a combined total of 389 biology and math textbooks in a week. The number of math textbooks sold was 45 less than the number of biology textbooks sold. How many textbooks of each type were sold?
Number of biology textbooks sold:
Number of math textbooks sold:
Number of biology textbooks sold: x
Number of math textbooks sold: x - 45
x + x - 45 = 389
2x - 45 = 389
2x = 434
x = 217
Number of biology textbooks sold: 217
Number of math textbooks sold: 217 - 45 = 172
So, 217 biology textbooks and 172 math textbooks were sold.