CAPEX and ROI calculation

Hi. I am trying to solve a question on my Kaplan exam kit but I don’t know how to consider CAPEX. The problem says the following:

Year 1 Year 2 Year 3
PBIT $ M 3.0 2.7 2.4
Asset base $ m 24 25 26

I have to calculate ROI, taking into consideration the following project and numbers:

Capital expenditure in years 1 and 2 and operating cash flow in year 3.

Year 1 Year 2 Year 3 NPV
$ m -0.5 -0.5 2 0.634

My understanding is that I add the cash flow to PBIT in year 3 and I add the expenses for the first two years to Asset base. But the solution to the question says that Asset base for Year 1 remains 24 m $, for Year 2 is 25.5 $ m and for Year 3 is 27 $m. I don’t understand quite well why is that.
Can you help me, please, with an answer?

Thank you,

Camelia