SOLUTION: A student bought a calculator and a textbook for a course in algebra. He told his friend that the total cost was $135 (without tax) and that the calculator cost $15 more than four

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A student bought a calculator and a textbook for a course in algebra. He told his friend that the total cost was $135 (without tax) and that the calculator cost $15 more than four       Log On


   

Question 1197758: A student bought a calculator and a textbook for a course in algebra. He told his friend that the total cost was $135 (without tax) and that the calculator cost $15 more than four times 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=135x=4y+15. Solve the system by using the method of substitution.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
The corresponding modeling system is
x%2By=135.......eq..1
x=4y%2B15......eq.2
_________________________
x%2By=135.......eq..1, substitute x from eq.2
4y%2B15%2By=135.....solve for y
5y=135-15
5y=120
y=24
go to
x=4y%2B15......eq.2, substitute y value

x=4%2A24%2B15
x=111

$111= the cost of a calculator and $24= the cost of the textbook