If the opening value at the beginning of the week was X, then at the end of the first day it was X+1.
If the opening value at the start of the second day was X+1, then at the end of the second day it was X+1+0 = X+1.
If the opening value at the start of the third day was X+1, then at the end of the third day it was X+1-5 = X-4.
if the opening value at the start of the fourth day was X-4, then at the end of the fourth day it was X-4-2 = X-6.
If the opening value at the start of the fifth day was X-6, then at the end of the fifth day it was X-6+3 = X-3. The closing value at the end of the week was -3 from the value at the beginning of the week.
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To find the amount of change over a time period, add all the changes in that period: 1 +0 -5 -2 +3 = -3.