Acme-Jones Company Uses a Weighted-Average Perpetual Inventory System

Acme-Jones Company uses a weighted-average perpetual inventory system.
August 2: 10 units were purchased at $12 per unit.
August 18: 15 units were purchased at $15 per unit.
August 29: 20 units were sold.
August 31: 14 units were purchased at $16 per unit.
What is the per-unit value of ending inventory on August 31?

A) $12.00
B) $13.80
C) $15.42
D) $16.00
E) $17.74