SOLUTION: A textbook store sold a combined total of 268 psychology and history textbooks in a week. The number of history textbooks sold was 58 less than the number of psychology textbooks

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Question 1073271: A textbook store sold a combined total of 268 psychology and history textbooks in a week.
The number of history textbooks sold was 58 less than the number of psychology textbooks sold.
How many textbooks of each type were sold?

Answer by Theo(13342)   (Show Source): You can put this solution on YOUR website!
let x = number of psychology books sold.
let y = number of history books sold.

a total of 368 books were sold.

x + y = 268

the number of history books sold was 58 less than the number of psychology books sold.

y = x - 58

you have 2 equations that need to be solved simultaneously.

they are:

x + y = 268
y = x - 58

since y = x - 58, then replace y in the first equation with x - 58 to get:

x + (x - 58) = 268

remove parentheses to get x + x - 58 = 268.

combine like terms to get 2x - 58 = 268.

add 58 to both sides to get 2x = 326.

divide both sides by 2 to get x = 163.

since x + y = 268, then y = 268 - 163 = 105

the number of psychology books sold is 163.
the number of history books sold is 105.

163 - 105 = 58.

there were 58 less history books sold than psychology books.


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