There are an infinite number of pairs:
(7, 8), (6, 9), (5, 10), ... , (0, 15), (-1, 16), (-2, 17), etc
then (7.1, 7.9), (6.1, 8.9), (5.1, 9.9), ... etc
and (7.2, 7.8), etc
and (7.3, 7.7), etc
etc
and then to 2 decimal places etc.
And then there are Irrational Numbers.
The two numbers that multiply to -30 and add up to 13 are 15 and -2. When you multiply 15 and -2, you get -30, and when you add them together, you get 13.
31
23
33
The two numbers that multiply to -15 and add up to 2 are 5 and -3. When you multiply 5 and -3, you get -15, and when you add them together, you get 2.
110 and -95
30
90
30
55
-23
29