Numbers: Percentages
Eg. If there are 10 red balls, 35 blue balls and 5 yellow balls in a box, then the box contains
20% red balls (10/50 × 100), 70% blue balls (35/50 × 100),
and 10% yellow balls (5/50 × 100).
% increase = [(increase in quantity) / (original quantity)] × 100
% decrease = [(decrease in quantity) / (original quantity)] × 100
