Question 553664
regular-------------------- 12 -------------x 
premium----------------------7-----------------------(x+0.21)

12*x+7(x+0.21)= 48.21

12x+7x+1.47=48.21

19x=48.21-1.47

19x=46.74
x= 46.74/19

regular $2.46
Premium $2.67 ( add 0.21 to regular price)