Which subtraction gives the answer 21?

To find out which subtraction results in the answer of 21, we need to perform each of the subtractions provided.

Starting with the first calculation, subtracting 9 from 30 gives us:

30 - 9 = 21

This tells us that the operation produces the correct result of 21, confirming that this particular subtraction satisfies the condition of the question.

When considering the other calculations:

• Subtracting 8 from 30 results in 22.
• Subtracting 7 from 30 produces 23.
• Subtracting 6 from 30 results in 24.

These results show that the other choices do not yield 21 as their outcome. Therefore, the only subtraction that results in the correct answer of 21 is indeed 30 minus 9. This gives us clarity on the concept of basic subtraction and reinforces the need for careful calculation when analyzing numerical operations.