Adding a Percent
Part of the Fundamentals section of Coddy's Algebra journey. Lesson 43 of 64.
Suppose a price has 25% tax added, and the total is 10. The price is x. The tax is 25% of the price, which is 0.25x. The price and the tax together come to 10, so the equation is:
x + 0.25x = 10
x and 0.25x are like terms, because x is 1x. Add them: 1.25x = 10. Divide both sides by 1.25: x = 8. Check the answer: 8 plus a quarter of 8 is 10.
A number plus 25% of itself is always 1.25x. A number minus 20% of itself is 0.8x. When you add the like terms first, a percent-increase problem becomes a one-step equation.
Challenge
MediumSolve the equation x + 0.5x = 12 for x.
Try it yourself
Solve for x
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 Equations2One-Step Equations
Undoing AdditionUndoing SubtractionUndoing MultiplicationUndoing DivisionInverse OperationsRecap: One-Step Equations5Tidying First
Like TermsTerms and Numbers MixedThe Distributive PropertyDistributing a SubtractionTidy, Then SolveRecap: Tidying First8Decimals and Percent
Decimal CoefficientsTwo-Step with DecimalsAdding a PercentPercent EquationsRecap: Decimals