A textbook store sold a combined total of 450 psychology and biology textbooks in a week. The number of psychology textbooks sold was two times the number of biology textbooks sold. How many textbooks of each type were sold?

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step-by-step explanation:

3 qrs + 3/2 xy hope this : /

step-by-step explanation:

333.74 ! should be your answer for this question

the solution, from the graphing of the two lines, is (3,2), i.e., x = 3, y = 2.