Speed is how fast something covers distance. Velocity is speed PLUS direction. They're often used interchangeably in everyday talk, but in physics they're different.
Speed
speed = distance / time
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Drive 240 km in 3 hours. Average speed?
240 / 3 = 80 km/h.
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60 km/h in m/s?
60 km/h = 60 × 1000 m / 3600 s = 16.67 m/s. (Roughly: divide km/h by 3.6.)