Mathematics Grade 8 15 min

Add and subtract fractions with like denominators in recipes

Add and subtract fractions with like denominators in recipes

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1

Introduction & Learning Objectives

Learning Objectives Identify fractions with like denominators in recipe contexts. Accurately add fractions with like denominators to combine ingredients. Accurately subtract fractions with like denominators to determine remaining quantities. Convert between mixed numbers and improper fractions when working with recipe measurements. Simplify fractional answers to their simplest form in recipe scenarios. Apply fraction operations to solve multi-step problems involving recipes and measurements. Ever wondered how a chef precisely combines ingredients or adjusts a recipe for more servings? 🧑‍🍳 It all starts with mastering fractions! In this lesson, you'll learn how to add and subtract fractions that have the same denominator, specifically within the practical context of c...
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Key Concepts & Vocabulary

TermDefinitionExample FractionA number representing a part of a whole, expressed as a numerator over a denominator.In a recipe calling for $\frac{3}{4}$ cup of flour, $\frac{3}{4}$ is a fraction. NumeratorThe top number in a fraction, indicating how many parts of the whole are being considered.In $\frac{3}{4}$, the numerator is 3, meaning 3 out of 4 parts. DenominatorThe bottom number in a fraction, indicating the total number of equal parts that make up the whole.In $\frac{3}{4}$, the denominator is 4, meaning the whole is divided into 4 equal parts. Like DenominatorsFractions that have the same denominator, making them easy to add or subtract directly.$\frac{1}{8}$ cup of sugar and $\frac{3}{8}$ cup of brown sugar both have a denominator of 8. Mixed NumberA number consisting of a whole...
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Core Formulas

Adding Fractions with Like Denominators $\frac{a}{c} + \frac{b}{c} = \frac{a+b}{c}$ To add fractions with the same denominator, add the numerators and keep the denominator the same. Always simplify the result if possible. Subtracting Fractions with Like Denominators $\frac{a}{c} - \frac{b}{c} = \frac{a-b}{c}$ To subtract fractions with the same denominator, subtract the numerators and keep the denominator the same. Always simplify the result if possible. Converting Mixed Numbers to Improper Fractions $A\frac{b}{c} = \frac{(A \cdot c) + b}{c}$ Multiply the whole number by the denominator, add the numerator, and place the result over the original denominator. This is often useful before adding or subtracting mixed numbers. Converting Improper Fractions to Mixed Num...

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Sample Practice Questions

Easy
In a recipe that calls for $\frac{3}{4}$ cup of flour, what is the mathematical term for the number 4?
A.Numerator
B.Denominator
C.Fraction
D.Mixed Number
Easy
A smoothie recipe requires $\frac{1}{5}$ cup of yogurt and $\frac{2}{5}$ cup of milk. What is the total volume of these two ingredients?
A.$\frac{3}{10}$ cup
B.$\frac{2}{5}$ cup
C.$\frac{3}{5}$ cup
D.$\frac{2}{10}$ cup
Easy
You have a measuring cup with $\frac{7}{8}$ cup of water. You pour out $\frac{4}{8}$ cup for a recipe. How much water is left in the measuring cup?
A.$\frac{3}{8}$ cup
B.$\frac{11}{8}$ cup
C.$\frac{3}{0}$ cup
D.$\frac{3}{16}$ cup

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