A student bought a calculator and a textbook for a course in algebra. He told his friend that the total cost was $ 145 (without tax) and that the calculator cost $10 more than twice the cost of the textbook. What was the cost of each item? Let x = the cost of a calculator and y = the cost of xty = 145 the textbook. The corresponding modeling system is Solve the system by using the method of substitution. (x = 2y + 10