Determine if the number are in proportion:
`21,119,30,170 `

Answer

To determine if the numbers 21, 119, 30, and 170 are in proportion, we need to check if the ratio of the first pair (21 and 119) is equal to the ratio of the second pair (30 and 170).

### Step-by-Step Solution:

1. **Write the Ratios**:
We start by writing the ratios of the two pairs:
\[ \text{Ratio 1} = \frac{21}{119} \]
\[ \text{Ratio 2} = \frac{30}{170} \]

2. **Simplify the First Ratio**:
To simplify \(\frac{21}{119}\), we can divide both the numerator and the denominator by their greatest common divisor (GCD). The GCD of 21 and 119 is 7.
\[ \frac{21 \div 7}{119 \div 7} = \frac{3}{17} \]

3. **Simplify the Second Ratio**:
Next, we simplify \(\frac{30}{170}\). The GCD of 30 and 170 is 10.
\[ \frac{30 \div 10}{170 \div 10} = \frac{3}{17} \]

4. **Compare the Ratios**:
Now we compare the simplified ratios:
\[ \frac{21}{119} = \frac{3}{17} \quad \text{and} \quad \frac{30}{170} = \frac{3}{17} \]
Since both ratios are equal, we can conclude that the numbers are in proportion.

5. **Conclusion**:
Therefore, we can say that the numbers 21, 119, 30, and 170 are in proportion.

### Final Answer:
Yes, the numbers 21, 119, 30, and 170 are in proportion.