### Home > PC > Chapter 12 > Lesson 12.1.3 > Problem 12-30

12-30.

Think about how you would write an equation for each sentence.

What would your system of equations look like?

How could you write your system as a matrix equation instead?

Where *x* = cost of 1 pencil, *y* = cost of 1 pen, *z* = cost of 1 eraser.

Solve for *x*, *y*, and *z* using your calculator.See problem 12-19 if you need more help.