The fraction 3/21 will reduce to 1/7. The fraction 5/34 will not reduce to 1/7, so they can not be equivalent fractions.

If the answer is not as clear as with this problem, you should rewrite the fractions with a common denominator. To this, multiply the first fraction by 34/34, which is equal to 1, and multiply the second fraction by 21/21, which is also equal to 1. Multiplying by 1 does not change the value of a number.

3/21 * 34/34 = 102/714

5/34 * 21/21 = 105/714

The two answers are not equal, so the fractions are not equivalent.

If the answer is not as clear as with this problem, you should rewrite the fractions with a common denominator. To this, multiply the first fraction by 34/34, which is equal to 1, and multiply the second fraction by 21/21, which is also equal to 1. Multiplying by 1 does not change the value of a number.

3/21 * 34/34 = 102/714

5/34 * 21/21 = 105/714

The two answers are not equal, so the fractions are not equivalent.