Grades, tips, tax, discounts, interest, and budget scenarios explained with percentage math.
Relative frequency times 100 gives percent of sample— distinguish sample percents from population parameters in wording.
Each category spend divided by total income shows proportion—50/30/20 rules are percent buckets, not rigid law.
Simple interest equals principal times rate times time—compound interest needs different formulas beyond one-period percent.
Discount applies to pretax subtotal in most retail math; tax applies after discounts unless problem states otherwise.
Tip equals bill times tip rate; split totals divide by party size after tax policy you choose.
Points earned divided by points possible yields exam percentage—weight categories separately for course grades.