A bookstore made 11000 dollars selling 3000 math books and 1000 physics books. A customer bought 1 math book and 1 physics book and paid 7 dollars. What is the price of each book? Choose the most appropriate option
A) 4 and 3	B) 1 and 6	C) 2 and 5	D) None	E) Cannot be determined
Solution:   Let x be the price of the math book and y be the price of the physics book   x + y = 7   3000 × x + 1000 × y = 11000   Use x + y = 7 to solve for y   x - x + y = 7 - x   y = 7 - x   Substitute 7 - x for y in 3000 × x + 1000 × y = 11000   3000 × x + 1000 × (7 - x) = 11000   3000x + 7000 - 1000x = 11000   2000x = 11000 - 7000   2000x = 4000   x = 2 since 2000 × 2 = 4000   Since 2 + 5= 
<gadget id="calculator">2 + 5</gadget>
<output>7</output>
7, y= 5   The price of a math book is 2 dollars and the price of a physics book is 5 dollars.   Answer 2 and 5
<result>C</result>
A bookstore made 11000 dollars selling 3000 math books and 1000 physics books. A customer bought 1 math book and 1 physics book and paid 7 dollars. What is the price of each book?