Simultaneous equations are two or more algebraic equations that share variables. They are solved at the same time (with the same variables).
Simultaneous equations can have one or more variables (unknown values) but the value of each variable is the same in all the sets of simultaneous equations:
Example: Two simultaneous equations share variables x and y, then the value of x is the same in both equations and the value of y is the same in both equations.
Then, simultaneous equations can have one or more unkown values (variables)