```
E = hf
```
where:
* E is the energy of the photon in joules (J)
* h is Planck's constant (6.626 x 10^-34 joules per second)
* f is the frequency of the photon in hertz (Hz)
Given the frequency of the FM station as 90.3 megahertz (MHz), we need to convert it to hertz:
```
f = 90.3 MHz = 90.3 x 10^6 Hz
```
Now, we can plug the values into the formula:
```
E = (6.626 x 10^-34 J s) x (90.3 x 10^6 Hz)
```
```
E = 6.00 x 10^-28 J
```
Therefore, the energy of a radio photon from the FM station broadcasting at 90.3 megahertz is 6.00 x 10^-28 joules.