Answer:Let x and (x-3) represent Elvira's and David's times respectively
D = r*t Â
Distances traveled are equal in this example***
14mph*x = 21mph(x-3)
solving for x
14x = 21x - 63
 63 = 7x
x = 9hr, the time that Elvira traveled.  David traveled 6hrs  (9hr-3hr = 6hr)
CHECKING our Answer***
14mph*9hr = 126mi = 21mph*6hr = 126mi
Step-by-step explanation: