A T-shirt shop charges $15 for an adult shirt and $12 for a youth shirt. The total charge for a shirt order was $489. Which equation can be used to represent x, the number of adult shirts sold and y,

A T-shirt shop charges $15 for an adult shirt and $12 for a youth shirt. The total charge for a shirt order was $489. Which equation can be used to represent x, the number of adult shirts sold and y, the number of youth shirts sold?