Respuesta :

Equation: 9x + 12 = 345
Answer: 37

Answer: 345 - 9x = 12 is the equation. Each book cost $37.

Step-by-step explanation: 345 - 12 = 333. This reveals that she spent $333 on books. We divide this by nine to find how much each cost. 333 / 9 = 37. In the equation, x = 37.