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 is an equation waiting to be written. "5 more than twice a number is 17":
2n + 5 = 17
Now it is a two-step equation: subtract 5, divide by 2, n = 6. Check against the sentence, not just the equation: twice 6 is 12, and 5 more is 17. Yes.
The routine for every word problem from here on: name the unknown, translate the sentence into an equation, solve, then read the answer back into the story to see that it makes sense. The middle step is the algebra you already know; the first and last steps are the new skill.
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