The video shows us how to solve a system of equations with the elimination method. First write the two equations one on top of the other, as it is going to be elimination method and it is recommended to write it in that way. Here the 2 equations are x+y=-3 and x-y=1. In the elimination method we need to add the 2 equations by columns. So adding it column wise we get to have 2x=-2 and solving this we will get the value of x=-1. Then you need to substitute this value of x in any of the two equations to find the value of y. By substituting this value of x in equation 1, we have -1+y=-3, and solving this we will get the value of y=-2. And in the same way he gives another set of equations which needs to be solved by elimination method, and this is also solved in the same way.