A textbook store sold a combined total of 327 psychology and history textbooks in a week. The number of history textbooks sold was 75 less than the number of psychology textbooks sold. How many textbooks of each type were sold?

201 psychology textbooks

126 history textbooks

Step-by-step explanation:

We let the number of psychology books be p, and

number of history books be h

Thus we can write 2 equations as:

1. p + h = 327

2. p - 75 = h

Now, we put equaiton 2 into equation 1 and solve for p first:

p + h = 327

p + (p-75) = 327

2p = 327 + 75

2p = 402

p = 402/2 = 201

So, 201 psychology textbooks. Now, we know p - 75 = h, hence

201 - 75 = h

h = 126

So, 126 history textbooks