7(3x+6)-2=6+5(4x-3)

Use the distributive property to reduce  7(3x + 6)  to get  21x + 42.

Use the distributive property to reduce  5(4x - 3)  to get  20x - 15.

7(3x + 6) - 2  =  6 + 5(4x - 3)

 21x + 42 - 2  =  6 + 20x - 15

Simplify each side:

     21x + 40  =  20x - 9

Subtract  20x  from both sides:

         x + 40  =  -9

Subtract  40  from both sides:

       x  =  -49