Problem: To m ounces of an m% solution of acid, x ounces of water are added to yield an (m−10)% solution. If m>25, then x is:
Answer Choices:
A. m−1010 m​
B. m−105m​
C. m−10m​
D. m−205m​
E. not determined by the given information
Solution:
m+xm⋅100m​​=100m−10​∴x=m−1010m​. The solution is valid for m>10. It, therefore, holds for m>25.