Add and subtract fractions with unlike denominators in recipes

Learning Objectives Identify fractions with unlike denominators in recipe contexts. Determine the least common multiple (LCM) of two or more denominators. Convert fractions to equivalent fractions with a common denominator. Accurately add fractions with unlike denominators when combining recipe ingredients. Accurately subtract fractions with unlike denominators when adjusting recipe quantities. Solve multi-step word problems involving fraction operations in recipes. Interpret fractional measurements in real-world recipe scenarios. Ever tried to double a recipe for cookies or cut it in half for a smaller batch? 🍪 What happens when the measurements aren't simple whole numbers? In this lesson, you'll learn how to confidently add and subtract fractions with differe...

TermDefinitionExample FractionA number that represents a part of a whole, expressed as a numerator over a denominator.In a recipe, $\frac{1}{2}$ cup of sugar means one part out of two equal parts of a cup. NumeratorThe top number in a fraction, indicating how many parts of the whole are being considered.In $\frac{3}{4}$ cup of flour, '3' is the numerator, meaning you have 3 parts. DenominatorThe bottom number in a fraction, indicating the total number of equal parts the whole is divided into.In $\frac{3}{4}$ cup of flour, '4' is the denominator, meaning the cup is divided into 4 equal parts. Unlike DenominatorsFractions that have different numbers in their denominators, meaning they represent parts of wholes divided into different numbers of pieces.$\frac{1}{2}$ cup an...

Finding a Common Denominator (LCM) To add or subtract fractions with unlike denominators, you must first find a common denominator, which is typically the Least Common Multiple (LCM) of the original denominators. For $\frac{a}{b} \pm \frac{c}{d}$, find LCM of $b$ and $d$. This rule is the first critical step. You cannot directly add or subtract fractions if they are not talking about the same 'size' of pieces. The LCM helps you find the smallest common 'size' to compare them. Converting to Equivalent Fractions Once the common denominator (LCM) is found, convert each original fraction to an equivalent fraction with the common denominator. Multiply both the numerator and the denominator by the same factor: $\frac{a}{b} = \frac{a \times k}{b \times k}$ where $...