Answer: Hence, there are 6 phones and 18 accessories sold.
Since we have given that 
Let number of phones sold be 'x' 
 
Let number of accessories sold be 'y'. 
 
Commission for every phone = $12 
 
Commission for every accessory = $3.50 
 
Total commission = $135 
 
And Difference between accessories and phones sold = 12 
 
According to question, we get that 
 
 
 
Using both the equations, we get that 
 
x=6 and y = 18