Proportions Math Example 5

Follow the full solution, then compare it with the other examples linked below.

Example 5

medium
Solve the proportion: x12=58\frac{x}{12} = \frac{5}{8}.

Solution

  1. 1
    Cross-multiply: 8x=12×5=608x = 12 \times 5 = 60.
  2. 2
    Divide both sides by 88: x=608=152=7.5x = \frac{60}{8} = \frac{15}{2} = 7.5.
  3. 3
    Check: 7.512=0.625\frac{7.5}{12} = 0.625 and 58=0.625\frac{5}{8} = 0.625 \checkmark

Answer

x=7.5x = 7.5
Cross-multiplication turns a proportion into a simple linear equation. Always verify the solution by substituting back into the original proportion.

About Proportions

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

Learn more about Proportions →

More Proportions Examples

Example 1 easy

Solve the proportion [formula].

Example 2 medium

If 5 notebooks cost [formula]8.75$, how much do 12 notebooks cost?

Example 3 easy

Solve: [formula].

Example 4 hard

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

← All Proportions Examples Proportions Concept