On a Florida multi-lane road you cannot safely move over for a stopped patrol car with flashing lights. What must you do?

The 20 MPH figure names the amount subtracted from the posted limit. It is not a target speed on its own. This answer recalls the number 20 without the word 'below', a misread that gives the right answer on a 40 MPH road and the wrong one at every other posted limit.

The Move Over Law contains no full-stop provision; the fallback when you cannot change lanes is a speed reduction, not stopping. This answer transfers the school-bus rule (full stop when flashers are out) onto any vehicle displaying warning lights, which the Move Over statute does not require.

The Move Over Law does not allow drivers to continue at the posted speed past a stopped patrol car with flashers when they cannot change lanes. The manual gives that case its own required action: a specific speed reduction, not driver-judged caution. This answer reads the Move Over Law as a lane-change duty only, so a driver who cannot change lanes concludes no further action is required beyond passing attentively at the posted limit.