Worked examples
Two examples
Example 1
Solve for x: x12 = 1536
- Cross-multiply: x × 36 = 15 × 12 = 180.
- Divide both sides by 36: x = 180 ÷ 36.
Answer: 5
Example 2
Solve for x: 47 = 28x
- Cross-multiply: 4 × x = 7 × 28 = 196.
- Divide both sides by 4: x = 196 ÷ 4.
Answer: 49
Where this is taught: Ratio, Proportion, and Percent, “Way 3: cross-multiplying”
The drill
Ten problems
How many:
Type each answer, then press Check my answers at the bottom. Commas in large numbers are fine.Write each answer on the line. The answer key, with the reasoning, is on the last page.