I have been using the below equation to calculate Watts required to reach a reference level Sound Pressure Level (SPL), however I cannot seem to successfully rearrange equation to find required Lsens. Can anyone help and show me how to rearrange this so that X (or in this case Lsens) is the subject?

Equations used to calculate the Watts:

dBW = Lreq - Lsens + 20 * Log (D2/Dref) + HR

W = 10 to the power of (dBW / 10)

Where:

Lreq = 105 SPL (required SPL at listener)

Lsens = 89dB (loudspeaker sensitivity (1W/1m))

D2 = 2.5m (loudspeaker-to-listener distance)

Dref = 1.0m (reference distance)

HR = 0dB (desired amplifier headroom)

dBW = (ratio of power referenced to 1 watt)

W = 249W (power required)