Question is in description.

Question

A student bought a calculator and a textbook for a course in algebra. He told his friend that the total cost was $105 (without tax) and that the calculator cost $30 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 the textbook. The corresponding modeling system is {x + y = 105

                                    {X =2y + 30

Solve the system by using the method of substitution.

Answer 1

x = cost of textbook in dollars

c = cost of calculator in dollars

 

x + c = $105

 

c = 2x + $30

 

substitute for c in the first equation

x + (2x + $30) = $105

3x =$75

x = $25

 

c = 2($25) + $30

c= $50 + $30 = $80