Question

hello. Euler method in differential equation system.
example is:
dx/dt=x+y
dy/dt=-y+8x

The problem is that I cant understand how to solve the problem which variable i Have to respect.

I know thaat I have to look for solution ( in general case) in forms
y=const*exp[k*x]; z=const2*exp[k*x]

In my case it would be
y=const*exp[k*x];x=const2*exp[k*x]
But i dont think that is correct because of x in the exp.

Please help me.