David can unload a delivery truck in 20 min.Allie can unload the same delivery truck in 35 min.if they work together,how long will the unloading take?

Relax

Respuesta :

Answer: 12.7 minutes

Step-by-step explanation:

1/20 + 1/35 =1

35t + 20t/20 x35 =1

55t/700=1

55t=700

700/55=12.7