Answer:
9 and -3
Step-by-step explanation:
Let the first number be x
Second number = y
x + y = 6
x = 15 - 2y
15 - 2y + y = 6
15 - y = 6
-y = 6 - 15
-y = -9 ( - sign gets cut cuz there is - sign at both the sides)
Therefore, first number = 9
x + y = 6
x = 9 = 6
x = -3
Therefore, second number = -3
Proof:
9 + (-3) = 6
Hope this helps
:)