More Than
Part of the Inequalities & Absolute Value section of Coddy's Math journey. Lesson 56 of 64.
You have 12 saved and add 5 every week. After how many weeks will you have more than 42? The savings after x weeks are 12 + 5x, and "more than 42" is a strict >:
12 + 5x > 42
5x > 30
x > 6
Strictly more than 6 weeks, so the first week that works is week 7. Whether the endpoint counts is the whole difference between "more than" and "at least", and in a story it is the difference between week 6 and week 7.
Read the phrase twice: the quantity on the left of the sign, the limit on the right, and the sign decided by the words. Then it is the algebra you know.
Challenge
A plant is 20 cm tall and grows 4 cm a week. After how many weeks will it be more than 56 cm tall?
The weeks are x. Solve 20 + 4x > 56 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 Inequalities & Absolute Value
1What an Inequality Is
The Four SignsA Picture on a LineClosed or OpenReading It BackwardsRecap: What an Inequality Is4Two-Step Inequalities
Two StepsSubtract, Then FlipWith a FractionA Bracket on the WayRecap: Two-Step Inequalities2Adding and Subtracting
Add to Both SidesSubtract from Both SidesNegatives in the MixSolve, Then DrawRecap: Adding and Subtracting5Variables on Both Sides
x on Both SidesGather Toward the LargerBrackets FirstAlways True, Never TrueRecap: Variables on Both Sides11From Words to Inequalities
At Least, At MostMore ThanA Budget That ShrinksTwo LimitsRecap: From Words3Multiplying and Dividing
Divide by a PositiveMultiply by a PositiveThe FlipDividing by a NegativeNegative FractionsRecap: Multiply and Divide6Graphing Solutions
From Inequality to PictureIs the Endpoint In?A Flip on the LineRecap: Graphing Solutions