Substituting the second equation in the first one we get:
[tex]3y+50+y=110.[/tex]
Adding like terms we get:
[tex]4y+50=110.[/tex]
Subtracting 50 from the above equation we get:
[tex]\begin{gathered} 4y+50-50=110-50, \\ 4y=60. \end{gathered}[/tex]
Dividing the above equation by 4 we get:
[tex]\begin{gathered} \frac{4y}{4}=\frac{60}{4}, \\ y=15. \end{gathered}[/tex]
Finally, substituting y=15 in the second equation we get:
[tex]\begin{gathered} x=3\cdot15+50, \\ x=45+50, \\ x=95. \end{gathered}[/tex]
Answer:
Cost of the calculator= $95.
Cost of the text book= $15.
