Ratios, Rates & the Number System

What you’ll learn

• A ratio compares two quantities; equivalent ratios multiply or divide both parts by the same nonzero number.
• A unit rate expresses "per one" of the second unit and makes fair comparisons across different sizes.
• Tape diagrams and double number lines visualize scaling in ratio problems.
• Percents, fractions, and decimals are different notations for the same comparisons.
• Divide fractions by multiplying by the reciprocal; use GCF/LCM to simplify and find common denominators.
• The number line orders all rational numbers; convert to decimals or common denominators when unsure.