ANSWER
92 miles
EXPLANATION
Let us make a sketch to represent the problem:
From the diagram, A is the starting point, B is the point she met her grandmother and C is the point she met her friend.
To find how far she is from her starting point, we have to simply subtract AB from BC.
That is:
BC - AB
= 212 - 120
= 92 miles
That is how far she is from her starting position.
