System of equations is nothing but a system which contains more than one linear equations. This system of equations can be solved to arrive at the solution of the system. A simple system of the linear equations can be a pair of equations. To solve this kind of system you can employ the substitution method. So take the two equation of the system. Solve for the value of y in the first equation in terms of x. Now take this value of y and substitute in the second equation y value. Now the second equation is a linear equation with one unknown variable x. Solve this second equation for the value of x. Substitute this value in any of the equations to obtain the value of y. This way by substituting you can find the solution to the equations. This video shows how to solve a system of linear equations by substitution.