Question Ssd showing less free space than it should

Sep 4, 2019
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If i check all my files on my ssd then it is 171 gb total, my system protection is using 10 gb and my ssd is total 232 gb so 232-(171+10)=51 gb of free space but it shows 43.5 gb of free space. What happened to my 7.5 gb space?