Because if we don’t deduct the investment in the subsubsidiary from the subsidiary’s net assets, we shall be double counting that amount
When sub invested in subsub effectively that investment acquired that much value of subsub’s assets. But by taking the TOTAL nci in subsub’s assets we are already including the indirect nci’s share of those subsub assets
So to then also take the nci share of subsidiary’s assets will be to double count the indirect nci in subsub