Begin by factoring 24 (the numbers that multiply together to make 24)
1&24, 2&12, 3&8, 4&6
Now, since you are looking for a negative 25, all of these combinations are negative since a negative x a negative = a positive.
The only combination that when added equals -25 is -1&-24.
and -1x-24=24
so the answer is -1&-24