Here's the linear equation and an explanation:
Equation: 2x + y = 15
Explanation:
* x: Represents the number of pens Anna bought.
* y: Represents the number of pencils Anna bought.
* 2x: Total cost of the pens, since each pen costs $2.
* y: Total cost of the pencils, since each pencil costs $1.
* 15: The total amount Anna paid.