I've got this explanation, about using Farther vs. Further:
The words farther and further both refer to a greater distance. However, farther is typically used when the distance is physical, and further is used when the distance is abstract or metaphorical. Further may be used to mean 'more' or 'to a greater degree.'
In following the explanation, there is a quiz, which gives back the right word to use (farther OR further). Please see below.
A. The further I have to drive, the more my back bothers me.
B. How much farther to Mimi's house?
I want to ask, if the other option work as well, in both sentences.