Answer:
see explanation
Step-by-step explanation:
Find equivalent routes for the directed lines, that is
(a)
FE = FA + AB + BE = b + a - 3b = a - 2b
(b)
BC = BE + ED + DC = - 3b + a + 2b = a - b
(c)
FC = FA + AB + BE + ED + DC
= b + a - 3b + a + 2b = 2a
