None, one or many - including infinitely many.
Although there is no graph, the number of solutions is 0.
It means that the equations are actually both the same one. When they're graphed, they both turn out to be the same line.
If a system of equations is inconsistent, there are no solutions.
The set of points the graphed equations have in common. This is usually a single point but the lines can be coincident in which case the solution is a line or they can be parallel in which case there are no solutions to represent.
As there is no system of equations shown, there are zero solutions.
In general, a system of non-linear equations cannot be solved by substitutions.
E. A. Grebenikov has written: 'Constructive methods in the analysis of nonlinear systems' -- subject(s): Asymptotic theory, Differential equations, Nonlinear, Iterative methods (Mathematics), Nonlinear Differential equations, System analysis
Isolating a variable in one of the equations.