Let's say Rhonda has m marbles.
The total number of marbles that Ammon has is m+<<+55=55>>55
Amon & Rhonda combined have m+(m+55) = 215
This means the total number of marbles they have together is 2m+55 = 215
2m=215-55
The total number of marbles that Rhonda has is m=160/2
Rhonda has m=80 marbles.
#### 80