Question 472497
Given
d= 19M
v=51MpH
As you have to find time in seconds  and speed v is given in hr convert units knowing that 1hr= 3600s 
v={{{51*(M/(3600*s))}}}= 0,0142 Mps
speed formula
v=d/t  where v - speed, d-distance, t - time

You have to find time, then t= d/v

subsitute for d and v