Carli and Angela share a cell phone plan and split the bill each month. Last month, their total bill was $109. Carli went over her data limit on her phone, so her share of the bill was $15 more than Angela's to account for the overage charge. Which system of equations represents this situation? A. c+a=15
c=a+109

B. c+a=109
c=a+15

C. c+a=109
a=c+15

D. c-a=15
c=a+109