The road is wet from rain. By how much does the handbook say you should cut your speed?

Why

The handbook gives three surfaces three different adjustments, and telling them apart is the whole of this question. A wet road costs you 5 to 10 mph. Packed snow costs you half your speed. Ice takes you down to no more than 5 mph, which is barely moving. Wet is the mildest of the three, and it is also the most common. Two warnings from the same section are worth carrying with it: the pavement can be very slippery when it first starts to rain, especially after a dry, hot spell, and shaded stretches, bridges and overpasses freeze before the rest of the road. On top of the speed change, turn on your windshield wipers, low-beam headlights and defroster.