2(5r+3) = 5

First remove the parentheses using the distributive property

                 2(5r + 3) = 5

                2·5x + 2·3 = 5

                   10x + 6 = 5

Get rid of all terms on the left which DO NOT contain x.  To get
rid of the " + 6 " we add " - 6" to boith sides:

                   10x + 6 =  5
                       - 6   -6
                ------------------
                   10x     = -1

Divide both sides by 10:

                    10x/10 = -1/10

                         x = -1/10

Edwin