Answer:
Either you're looking for "one number" that is added to -1 and multiplied to -6 to give "another number" which you didn't mention.
Or
You're looking for "two numbers" when added together they equal -1 and when multiplied they make -6.
In the second case, you're looking for :
2 and -3
In the first case, you have to tell us the second number. So, I am guessing you're asking about the second case.