Abigail works as a salesperson at an electronics store and sells phones and phone accessories. Abigail earns a $12 commission for every phone she sells and a $3 commission for every accessory she sells. On a given day, abigail made a total of $258 in commission and sold 6 more accessories than phones. Write a system of equations that could be used to determine the number of phones sold and the number of accessories sold. Define the variables that you use to write the system.