ABC (MCQ)

A company is changing its costing system from taditional absorption costing based on labour hours to ABC. It has overheads of $156000 which are related to taking deliveries

The delivery information about each product is :-
Total units required Delivery size

X 1000 200
Y 2000 400
Z 3000 1000

Total labour costs are $360000 for 45000 hours. Each unit of each product takes the smae number of direct hours.

Assuming that the company uses the number of deliveries as its cost driver, what is the increase or decrease in unit cost for “Z” arising from the change from absorption costing to ABC?
a) decrease $22 per unit
b) Increase of $22 per unit
c) Decrease of $30 per unit
d) Increase of $30 per unit

# I calculated the answer of unit cost by absorption costing and it was correct but as i calculated and checked Unit cost by ABC, my answer was incorrect
according to my calculation Unit cost by ABC would be

156000 * 3/13 =36000
36000/3000 = 12 per unit

but in answers, they calculated it as

156000/13= 12000
12000/3000= 4
26-4= 22 decrease

Can you please explain this ?