The percent of change would be -33.3% which would then equal a 33.3% decrease (when decimal is rounded)
what I did was turn 1/4 and 1/2 into decimals to make it easier to solve
The formula of a cirumference of a circle:

r - radius
We have r = 10. Substitute:

<h3>Answer: C = 20π</h3>
3a^3 is the answer
Hope that helps