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Study Guides > Prealgebra

Introduction to Adding and Subtracting Fractions with Different Denominators

Two pieces of coffee cake with crumb topping on a green plate Does Maria have enough sugar to make her favorite coffee cake?
Have you ever needed to add or subtract fractions with different denominators? One place this often comes up is in the kitchen. For example, Maria's coffee cake recipe calls for 2/3 cup of sugar in the cake, and 1/4 cup of sugar in the crumb topping. Maria notices she's getting low on sugar, so she wants to make sure she has enough before she starts mixing the batter. How much sugar does she need in all? To figure it out, Maria needs to add fractions with different denominators. In this section, you'll learn how to find the least common denominator and convert fractions in order to add and subtract.

Learning Outcomes

By the end of this section, you will be able to:
  • Find the least common denominator (LCD)
  • Convert fractions to equivalent fractions with the LCD
  • Add and subtract fractions with different denominators
  • Identify and use fraction operations
  • Use the order of operations to simplify complex fractions
  • Evaluate variable expressions with fractions
 

readiness quiz

Before you get started, take this readiness quiz. 1) Find two fractions equivalent to [latex]\frac{5}{6}[/latex].

Answer: Answers may vary. Correct answers include [latex]\frac{10}{12},\frac{15}{18},\frac{20}{24},\frac{25}{30}\text{ and }\frac{30}{36}[/latex]

If you missed this problem, review the following video. https://youtu.be/8gJS0kvtGFU 2) [ohm_question]146164[/ohm_question] If you missed this problem, review the following video. https://youtu.be/fK7-w77cgVQ
 

Licenses & Attributions

CC licensed content, Shared previously

  • Coffee Cake. Authored by: Chelsea Wa. Located at: https://commons.wikimedia.org/wiki/File:Apple_coffee_cake.jpg. License: CC BY-SA: Attribution-ShareAlike.
  • Ex: Determine Equivalent Fractions. Authored by: James Sousa (Mathispower4u.com). License: CC BY: Attribution.
  • Ex 1: Simplify an Expression in Fraction form (Order of Operations). Authored by: James Sousa (Mathispower4u.com) . License: CC BY: Attribution.

CC licensed content, Specific attribution