Do you need to buy a new laptop?

Is this how your parents react when you ask them to buy it?

Homer Simpson disappearing into a garden hedge

If you need to buy that laptop on your own, you can use algebra to figure out how to save up for it!

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Here's The Plan!

Run through these steps when you're planning for a purchase.

Once you decide what you want to buy, answer the 5 questions below:

A cartoon character stroking its chin, saying

1. How much does it cost?

2. How much money do you have now?

3. How much more money do you need to save to buy it?

4. How will you earn that amount?

5. How much time will it take to save it?

The next step is to set up an algebraic equation to answer the questions.

A woman thinks about a problem. Algebraic equations float in front of her eyes.

Example In Action

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Luna is a high schooler who has a part-time job babysitting every Saturday.

She earns $60 every month from that. She has $356 saved up in her bank account. She wants to buy a new laptop that costs $1000, and she wants it in time for final exams in 6 months.

Set up an equation to see if she can reach her goal:

  • Part A: Will she have enough money to buy the laptop in 6 months?

  • Part B: If not, how many months will it take her to save for the laptop?

Answer the 5 questions 👉

We know that Luna has decided to buy a laptop.

  1. Find out how much it costs.

    The laptop costs $1000.

  2. How much money does she currently have?

    She has $365 saved up.

  3. How much more money does she need to save to buy it?

    See calculation below.

  4. How will she earn that amount?

    She saves the earnings from her part-time job. She earns $60 per month.

  5. How much time will it take to save it?

    See the calculation in the next step.

Use the formula below to create an algebraic equation to find the answer:

Total cost = amount saved up + amount earned x time (per hour/day/week/month, etc). Unknown values are variables labelled x.

Setting Up The Equation: Part A

Will Luna will have enough money to buy the laptop in 6months?

Follow this equation to see if she will or not.

S = $365 + 60X; S = total amount saved, X = number of months that money is earned

Here, the total amount she saves at the end of 6 months is $725.

👉 Luna won't have enough money to buy the laptop in 6 months.

$1000 - $725 = $275

👉 She needs $275 more to reach her goal of $1000.

Setting Up The Equation: Part B

How many months will it take Luna to save up for the laptop?

To answer the second part of the question, identify the known information & place it in the equation:

$1000 = $365 + 60 X

Here, x = 10.58, but this value isn't a whole number, so we need to round it up to 11.

👉 It will take Luna 11 months to save up enough to buy the laptop.

It's Your Turn Now!

Can you figure out the solution to the problem below?

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Question: Ruby broke her camera, so she'd like a new one that costs $250. She wants to buy it in 5 weeks. How much does she need to save each week?

Hint: Place the values you know into the algebraic formula shown above and find the unknown value.


How much does Ruby need to save each week?

Worked Out Solution To The Quiz Question

👉 Ruby has to save $50 each week to get her camera in 5 weeks.

Take Action

A mother cheering on her children with pom poms Impress your parents with your financial planning skills!


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This Byte has been authored by


Chitra Krishnan

Lifelong Learner