a) The value of n-m is positive.

b) The value of n+m is positive.
c) The value of n+m is negative.
d)The value of -(n-m) is negative.
which one is correct?

To determine which choices are correct, we need to understand the concepts of positive and negative values in mathematics.

a) The value of n-m is positive. This is not necessarily correct. If n is a larger number than m, then n-m would be positive. However, if n is smaller than m, then n-m would be negative. Therefore, this statement is not always true.

b) The value of n+m is positive. This is also not necessarily correct. If both n and m are positive numbers, then their sum (n+m) would be positive. However, if either n or m is negative, then their sum could be negative. Therefore, this statement is not always true.

c) The value of n+m is negative. This is not correct. Adding two positive numbers will always yield a positive sum. Therefore, this statement is never true.

d) The value of -(n-m) is negative. This is correct. The negative sign in front of (n-m) will change the sign of the value. If n is larger than m, then -(n-m) would be negative. If n is smaller than m, then -(n-m) would be positive. Therefore, this statement is always true.

So, the correct statement is d) The value of -(n-m) is negative.