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=15 c=a+109 d. c+a=109 a=c+15