Add and subtract fractions with unlike denominators in recipes

Learning Objectives Identify the least common denominator (LCD) for two or more fractions. Convert fractions with unlike denominators into equivalent fractions with a common denominator. Accurately add two or more fractions with unlike denominators. Accurately subtract two fractions with unlike denominators. Simplify a final fractional answer to its lowest terms. Solve one- and two-step word problems involving the addition and subtraction of fractions in recipe contexts. Have you ever tried to bake cookies and needed to combine 1/2 cup of sugar and 1/4 cup of brown sugar? 🍪 Let's figure out how much that is all together! In this lesson, you will become a kitchen math whiz! We will learn the secret to adding and subtracting fractions that have different bottom numbers,...

TermDefinitionExample Unlike DenominatorsThe bottom numbers (denominators) of two or more fractions are different.In the fractions 1/2 and 1/3, the denominators are 2 and 3. They are unlike. Common DenominatorA number that is a common multiple of the denominators of two or more fractions. It's a bottom number that both fractions can share.For 1/2 and 1/3, a common denominator is 6, because both 2 and 3 can multiply to get 6. Least Common Denominator (LCD)The smallest possible number that can be used as a common denominator for two or more fractions. It is the Least Common Multiple (LCM) of the denominators.For 1/4 and 1/6, common denominators are 12, 24, 36... The LCD is 12. Equivalent FractionsFractions that have different numerators and denominators but represent the same value.1/2...

Finding the Least Common Denominator (LCD) List the multiples of each denominator. The smallest number that appears in both lists is the LCD. Use this first step whenever you need to add or subtract fractions with unlike denominators. It helps you find the right 'size' for your fraction pieces so you can combine them. Addition with Unlike Denominators a/b + c/d = (a*d)/(b*d) + (c*b)/(d*b) = (ad + cb) / bd To add fractions with different denominators, you must first convert them into equivalent fractions with a common denominator. Then, add the new numerators and keep the common denominator the same. Subtraction with Unlike Denominators a/b - c/d = (a*d)/(b*d) - (c*b)/(d*b) = (ad - cb) / bd To subtract fractions with different denominators, you must first co...