The two numbers that add up to 4 and multiply to 20 are -4 and 5. When you add them together, -4 + 5 equals 1, which does not satisfy the addition requirement. Instead, the correct numbers are -2 and -10, since -2 + -10 equals -12 and -2 * -10 equals 20. However, there are no real numbers that satisfy both conditions simultaneously.
20
4 and 5
20
84
-21
104
29
2584
0.6592 and 30.3408 (to 4 dp).
-27
26
-70