Can someone explain how to do a, b and c please?

The following is an extract of an article from the NZ Herald Michael Hill warns of $21 million hit to first-half earnings on US exit 8 Feb, 2018 4:43pm Michael Hil International expects first-half earnings will more than halve with A$20 million ($21.7m) coming from the jewellery chain's exit from the US and scaling back its Emma & Roe branded store footprint The Brisbane-based company said earnings before interest and tax was about A$20m in the six months ended December 31, down from A$40m a year earlier Of that, about AS8.4m arises from onerous lease provisions and another AS11.4m from impairment charges on property, plant and cquipment, it said in a statement. "Despite the one-off accounting impacts from store closures, the decisive actions taken to reduce the Emma & Roe store footprint and exit the US are critical to strengthening the foundations of Michael Hill International as we focus orn building significant long-term value in our core business across Australia, New Zealand and Canada," chief executive Phil Taylor said. Last month the jewellery chain announced plans to quit its decade-long investment in the US and overhaul itsEmma & Roe brand into demi-fine products with a smaller physical store footprint At the time of the announcement, the company said it expected to write down the Emma & Roe assets by AS7m, but wasn't sure of the financial impact from the US exit Michael Hill is still negotiating with landlords over the Emma & Roe stores and US exit and hasn't determined the final timing of cash cost of the closures, it said The dual-listed shares fell 2.1 per cent to A$1.18 on the ASX. Required a) Explain the possible reason of Michael Hill to recognise an impairment of property, plant and equipment in December 2017. b) Is this impairment considered material? Why? c) Do the journal entry of the asset impairment recorded by Michael Hill on 31 December 2017