Answer: The percent increase is 60%
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Work Shown:
A = old value = 5
B = new value = 8
C = percent change
C = 100*(B - A)/A
C = 100*(8 - 5)/5
C = 100*(3/5)
C = 100*0.6
C = 60%
The fact that C is positive indicates we have a percent increase.
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If we apply 60% to 5 then we have 0.60*5 = 3
So we've increased by $3 to go from 5 to 5+3 = 8.