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Da VIP Academy / GED / Math / Ratios & Proportional Reasoning

Proportions & Scale

Set up and solve proportions, including scale drawings and maps.

Practice this skillAll Math skills

How it works

Cross multiply

If 5/8 = x/40, then 8x = 5 × 40 = 200, so x = 25. Keep matching units across from each other.

Scale problems are proportions

If 1 inch stands for 25 miles, then 3.5 inches stands for 3.5 × 25 = 87.5 miles.

Worked examples

  1. Solve 5/8 = x/40.

    1. Cross multiply: 8x = 200.
    2. Divide both sides by 8.
    3. x = 25.

Words to know

Proportion
An equation stating two ratios are equal.

Test-day tips

  • • Write the proportion with words first, then swap in numbers.
Try Proportions & Scale practice