Q11 June 2015 past exam

Hi,
I’m doing this following question and I have a problem:

Wilmslow acquired 80% of the equity shares of Zeta on 1 April 2014 when Zeta’s retained earnings were $200,000.During the year ended 31 March 2015, Zeta purchased goods from Wilmslow totalling $320,000. At 31 March 2015, one quarter of these goods were still in the inventory of Zeta. Wilmslow applies a mark-up on cost of 25% toall of its sales.
At 31 March 2015, the retained earnings of Wilmslow and Zeta were $450,000 and $340,000 respectively.
The question is to calculate the retained earnings of Wilmslow’s consolidated statement in financial position.

Answer:

Retained earnings:
$
Wilmslow 450,000
Post acq Zeta ((340 – 200) x 80%) 112,000
URP in inventory (320,000 x ¼ x 25/125) (16,000)
––––––––
546,000
I have calculated as I calculate the URP for 16,000 then deduct to the retained earning of Zeta for the year ended 31 March 2015 so I get 124,000. After that I multiplied with 80% as the percentage of acquisition.
I dont understand why the answer did not multiply the URP with 80%.
Thanks