Proportions Examples in Math

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Proportions.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Math.

Concept Recap

An equation stating that two ratios are equal, used to find an unknown when three of the four values are known.

If 2 candies cost 1, then 4 candies cost 2β€”same proportion.

Read the full concept explanation β†’

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Proportions let you find unknown values that maintain a ratio.

Common stuck point: Setting up the proportion so matching units are in the same position (both in numerator or both in denominator).

Sense of Study hint: Write the units next to each number in both fractions and make sure the same unit is on top in both ratios.

Worked Examples

Example 1

easy
Solve the proportion \frac{x}{6} = \frac{10}{15}.

Solution

  1. 1
    Cross-multiply: 15x = 6 \times 10 = 60.
  2. 2
    Divide both sides by 15: x = \frac{60}{15} = 4.
  3. 3
    Check: \frac{4}{6} = \frac{2}{3} and \frac{10}{15} = \frac{2}{3} \checkmark

Answer

x = 4
A proportion states that two ratios are equal. Cross-multiplying converts the proportion into a simple linear equation that you can solve for the unknown.

Example 2

medium
If 5 notebooks cost \8.75$, how much do 12 notebooks cost?

Example 3

medium
Solve the proportion: \frac{x}{12} = \frac{5}{8}.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy
Solve: \frac{3}{7} = \frac{9}{x}.

Example 2

hard
A car travels 180 km on 15 litres of fuel. How many litres are needed for a 540 km trip?

Background Knowledge

These ideas may be useful before you work through the harder examples.

ratiosequations