The price of the textbook is $165.
Work Step by Step
Let X represent the price of the calculator. The textbook price is $45 more than the price of the calculator. Thus, we obtain that the textbook price is 45 + X Together, the calculator and the mathematics textbook cost 285 dollars. So: X + 45 + X = 285 2X + 45 = 285 Subtract 45 from both sides: 2X = 240 Divide both sides by 2: X = 120 Since the price of the textbook is 45 + X and X = 120, the price of the textbook is 45 + 120 = 165 dollars.