We have the next equation
[tex]5x+7=2\mleft(6x-14\mright)+56[/tex]First we will simplify the equation
[tex]5x+7=12x-28+56[/tex]we sum like terms
[tex]5x+7=12x+28[/tex]we subtract 7 on both sides
[tex]5x+7-7=12x+28-7[/tex][tex]5x=12x+21[/tex]we subtract -12x on both sides
[tex]5x-12x=21[/tex][tex]-7x=21[/tex]we divide -7 into both sides
[tex]\frac{-7}{-7}x=\frac{21}{-7}[/tex][tex]x=-3[/tex]the value of x is -3