2x + 5 = 3

2x + 5  =  3

                                    Subtract  5  from both sides of the equation.

2x + 5 - 5  =  3 - 5

                                    2x + 5 - 5 = 2x   and   3 - 5 = -2

2x  =  -2

                                    Divide both sides of the equation by  2 .

2x/2  =  -2/2

                                    2x/2 = x     and     -2/2 = -1

x  =  -1

You can plug this back into the original equation to see if it is true.

2(-1) + 5  =  3   ?

-2 + 5  =  3      This is true.