The speed of sound in air at 30 degrees Celsius is approximately 349 meters per second (m/s) or 1,145 feet per second (ft/s).

Here's how to calculate it:

* Formula: The speed of sound in air is calculated using the following formula:

```

v = 331.5 + 0.6T

```

where:

* v is the speed of sound in m/s

* T is the temperature in degrees Celsius

* Calculation:

```

v = 331.5 + 0.6 * 30

v = 331.5 + 18

v = 349.5 m/s

```

Note: This is an approximation as the speed of sound can be affected by factors like humidity and altitude.