The percentage increase or decrease can be calculated by :
[tex]\%change=\frac{New-Orig}{Orig}\times100[/tex]7. New = 13, Orig = 10
% change = [(13 - 10)/10] x 100 = 30% (Increase)
8. New = 3, Orig = 5
% change = [(3 - 5)/5] x 100 = -40% or 40% (decrease)