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Question

Find the missing number in this proportion.

10
Division Line = Division Line
15 21

Answer 1

To find the missing number in the proportion \( \frac{10}{15} = \frac{x}{21} \), we can cross-multiply:

\[ 10 \times 21 = 15 \times x \]

This simplifies to:

\[ 210 = 15x \]

Now, divide both sides by 15:

\[ x = \frac{210}{15} \]

Calculating that gives:

\[ x = 14 \]

Thus, the missing number is:

14