Question

A textbook store sold a combined total of 209 history and math textbooks

in a week. The number of math textbooks sold was 75 less than the
number of history textbooks sold. How many textbooks of each type
were sold?

Answer 1

67 math, 142 history

Explanation:

lets say the number of math textbooks was x and the number of history textbooks is y. we have x+y=209 and x=y-75. we can plug the second equation into the first to get y-75+y=209. simplfy to get 2y=284 so y=142. since x=y-75, x=67