system of linear equations

 
Suppose in one year, total revenues from digital sales of pop/rock, tropical (salsa/merengue/cumbia/bachata), and urban (reggaeton) Latin music in a certain country amounted to $27 million. Pop/rock music brought in twice as much as the other two categories combined and $11 million more than tropical music. How much revenue was earned from digital sales in each of the three categories?