Lease_BPP Study text_Bulwell

Dear sir,
Sorry, but may I ask you a further question, This is a question on the study text of BPP.

Bulwell Aggregates Co entered into a three-year contract to obtain three lorries on 1 January 20X1. The contract met the IFRS 16 criteria to be classified as a lease and the initial measurement of the right-of-use asset was $54,000. The agreement states that Bulwell Aggregates will pay a deposit of $9,000 on 1 January 20X1, and two annual instalments of $24,000 on 31 December 20X1, 20X2 and a final instalment of $20,391 on 31 December 20X3. Ownership will pass to Bulwell at the end of the lease term.
Interest is to be calculated at 25% on the balance outstanding on 1 January each year and paid on 31 December each year.
The depreciation policy of Bulwell Aggregates Co is to depreciate the right-of-use asset arising from the lease of the vehicles over a four year period using the straight line method.
Required
Show the entries in the statement of profit or loss and statement of financial position for the years 20X1, 20X2, 20X3. This is the only lease transaction undertaken by this company.

And below is the answer from the textbook:

STATEMENTS OF PROFIT OR LOSS (EXTRACTS)
20X1 20X2 20X3 20X4
Finance cost 11,250 8,063 4,078
Depreciation on lorries 13,500 13,500 13,500 13,500
STATEMENTS OF FINANCIAL POSITION AT 31 DECEMBER (EXTRACTS)
20X1 20X2 20X3 20X4
Non-current assets
Right-of-use assets 54,000 54,000 54,000 54,000
depreciation 12,500 25,000 37,500 50,000
Carrying amount 41,500 29,000 16,500 4,000

My question is why in the P/L, depreciation charge is 13,500 but in the SFP it is 12,500.
is it an error or my fault?

Thanks a lot!