
Answer:
a) 7a/8; b) 5a/8 Â
Step-by-step explanation:
Given:
AP = 2PQ = 2QB
Calculations:
1. A to the midpoint of QB
    a = AP + PQ + QB
If 2PQ = 2QB.
  PQ = QB and
  AP = 2PQ
∴    a = 2PQ + 2PQ = 4PQ
  PQ = a/4
  AP = 2PQ = a/2
Let M be the midpoint of QB.
AM = AP + PQ + QM
   = a/2 + a/4 + a/8
   = 7a/8
2. Midpoints of AP and QB
Let N be the midpoint of AP
NM = NP + PQ + QM
   = a/4 +a/4 + a/8 =
   = 5a/8
Â