Question

A textbook store sold a combined total of 217 biology and sociology textbooks in a week. The number of biology textbooks sold was 59 more than the number of sociology textbooks sold. How many textbooks of each type were sold?

Answer 1

79 sociology textbooks and 138 biology textbooks

Explanation:

Create a system of equations, where b is the number of biology books and s is the number of sociology books:

b + s = 217

b = s + 59

Solve by substitution by substituting s + 59 for b into the first equation:

b + s = 217

s + 59 + s = 217

Add like terms and solve for s:

2s = 158

s = 79

So, there were 79 sociology books. To find the number of biology books, substitute 79 in for s into the equation b = s + 59

b = s + 59

b = 79 + 59

b = 138

So, 79 sociology textbooks and 138 biology textbooks were sold.