We use ‘tardar + amount of time + en + infinitive” to say how long it takes for someone (person, animal, or thing) to do something; where the person, animal, or thing will be the subject of the sentence.
Tardamos dos horas en llegar a Madrid en avión (I took us three hours to get to Madrid by plane).
El avión tardó más de tres horas en llegar a Tenerife (The plane took more than three hours to reach Tenerife.)
¿Cuánto se tarda en llegar de Málaga a Marbella en bicicleta? (How long does it take to go from Málaga to Marbella by bike?)
Be careful, because TARDAR also means to take too much time, as in delaying.
El tren tarda en llegar (the train is late in arriving.)
Also pay attention not mistake verb tardar with the adjective tarde (late).
El tren llegó tres horas tarde (the train arrived three hours late.)