So you need the solve for x and y ?
from 8x-y = 10,
y = 8x -10
Plug this in other equation.
8x-10 = x^2 +12x + 30
Re-arrange and combine like terms,
x^2 +12x -8x +30+10 = 0
x^2 +4x +40 = 0
This does not have any real solutions.
So there are no real values of x and y satisfying the 2 equations.
Are you sure the question is correct? or if this question belongs to complex numbers topic?