bbp revision kit mcqs 57

direct material cost all of the parts currently proposed for the webcam are bespoke parts.however,most of these can actually be replaced with standard parts costing 55% less.however,three of the bespoke parts which currently account for 20% of the estimated direct material cost,cannot be replaced,although an alternative supplier charging 10% less has been sourced for these parts. direct material cost is $40.

40*45%= 18
18*80%=14.4 i solved it on my own but i don’t understand the last one line why we are taking 90% of 8 (40*20%) as a new cost and making part of above cost which is $14.4 kindly help sir.