Proportions Math Example 3

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

Example 3

easy
Solve: 37=9x\frac{3}{7} = \frac{9}{x}.

Solution

  1. 1
    Cross-multiply: 3x=7×9=633x = 7 \times 9 = 63.
  2. 2
    Divide: x=633=21x = \frac{63}{3} = 21.

Answer

x=21x = 21
Apply cross-multiplication to turn the proportion into a one-step equation.

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 4 hard

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

Example 5 medium

Solve the proportion: [formula].

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