Answer
y = -x
y = (3/2)x - 5
Explanation.
the sum of 2 numbers is 0
That will be,
x + y = 0
Adding x both sides we get,
y = -x
The other statements is,
3x - 2y = 10
Adding 2y on both sides we get,
3x = 10 + 2y
Subtracting 10 both sides we get,
2y = 3x - 10
Dividing both sides by 2 we get,
y = (3/2)x -5