To simplify this expression, we need to evaluate the exponentiation first.

First, let's evaluate -25^7. Since the exponent is odd, the negative sign applies to the entire expression.

-25^7 = -(25^7)

Next, let's evaluate 32^3.

32^3 = 32 * 32 * 32 = 32,768

Now, let's substitute these values back into the original expression:

-25^7:32^3 = -(25^7):32^3 = -(25^7) / 32,768