There are two ways to know the NB wattage, which shows the voltage-V & current-I
(1) To check the label on notebook bottom.
(2) To check the label on original adapter
The label shows,
The wattage
Voltage(V) x Current (A) = NB Wattage
19V x 4.74A = 90W

19V x 3.42A = 65W