Four.
4
There are three kinds:the equations have a unique solutionthe equations have no solutionthe equations have infinitely many solutions.
simultaneous equations
A consistent system of equations is one in which there is at least one set of values for the variables that satisfies all the equations simultaneously. In graphical terms, this means that the lines or planes represented by the equations intersect at one or more points. A consistent system can be classified as either independent (with a unique solution) or dependent (with infinitely many solutions). In contrast, an inconsistent system has no solutions, meaning the equations represent parallel lines or planes that do not intersect.
It is a set of equations, which is also called a system of equations. There may be no solution, a single (unique) solution or more than one - including infinitely many.