Sentences into Equations
Part of the Fundamentals section of Coddy's Algebra journey. Lesson 51 of 64.
A sentence with "is" or "equals" in it can be written as an equation. The word "is" becomes the equals sign. Take the sentence "5 more than twice a number is 17". Call the number n and translate:
2n + 5 = 17
Now you have a two-step equation. Subtract 5 from both sides, then divide by 2, and you get n = 6. Check the answer against the sentence, not only against the equation. Twice 6 is 12, and 5 more than 12 is 17. The answer is right.
Every word problem follows the same steps. Name the unknown with a letter. Translate the sentence into an equation. Solve the equation. Then check the answer against the original words, including any units or conditions the problem gives.
Challenge
Medium“4 less than three times a number is 20.” Write this sentence as an equation, using n for the number. Do not solve it.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Fundamentals
1What an Equation Is
The EquationFinding the UnknownThe Same to Both SidesSolved Means AloneRecap: First Equations4Two-Step Equations
Two Layers to UndoSubtract, Then DivideAdd, Then DivideA Division InsideNegatives in Two StepsRecap: Two-Step Equations7Fractions in Equations
A Fraction CoefficientClearing One DenominatorTwo DenominatorsA Fraction Around a SumCross-MultiplyingRecap: Fractions10From Words to Equations
Phrases into ExpressionsSentences into EquationsConsecutive NumbersAge and MoneyA Perimeter ProblemRecap: Words2One-Step Equations
Undoing AdditionUndoing SubtractionUndoing MultiplicationUndoing DivisionInverse OperationsRecap: One-Step Equations5Tidying First
Like TermsTerms and Numbers MixedThe Distributive PropertyDistributing a SubtractionTidy, Then SolveRecap: Tidying First