Question

A textbook store sold a combined total of 219 history and chemistry textbooks in a week. The number of chemistry textbooks sold was 45 less than the number of history textbooks sold. How many textbooks of each type were sold?

Answer 1

Answer: 87 Chemistry and 132 history textbooks.

Step-by-step explanation:

Let x represent the number of chemistry textbooks that was sold.

Let y represent the number of history textbooks that was sold.

The textbook store sold a combined total of 219 history and chemistry textbooks in a week. This means that

x + y = 219 - - - - - - - - - - - -1

The number of chemistry textbooks sold was 45 less than the number of history textbooks sold. This means that

x = y - 45

Substituting x = y - 45 into equation 1, it becomes

y - 45 + y = 219

2y = 219 + 45 = 264

y = 264/2 = 132

x = y - 45 = 132 - 45

x = 87

Answer 2

Answer:

132 history textbooks, 87 chemistry textbooks

Step-by-step explanation:

$C + H = 219\\C = H - 45$

$1. H - 45 + H = 219\\2. 2H = 264\\3. H = 132$

H = 132,

C = 132 - 45 = 87