For this case, the first thing we must do is define variables.
We have then:
x = Carli's bill
y = Angela's bill
We have then:
"their total bill was $ 109"
x + y = 109
"Carli went over her data limit on her phone, so her share of the bill was $ 15 more than Angela's"
x = y + 15
Answer:
A system of equations that represents this situation is:
x + y = 109
x = y + 15
