Let's assume Rhonda has X number of marbles.
Since Amon owns 55 marbles more than Rhonda, Amon has X + 55 marbles.
Together, they have X + (X + 55) = 215 marbles.
Combining like terms, we have 2X + 55 = 215.
Subtracting 55 from both sides, we have 2X = 160.
Dividing both sides by 2, we have X = 80.
Therefore, Rhonda has 80 marbles.
#### 80
The answer is: 80
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
Amon & Rhonda combined have 215 marbles. If Amon owns 55 marbles more than Rhonda, how many marbles does Rhonda have?

### Answer:
