3x+4(x-8)-x=3/5(10x+15)

Multiply out the parentheses terms. Then combine the "x" terms and the constant terms separately, and put them on opposite sides of the equation. Then divide both sides by the coefficient of x.

The first step in the process results in
6x -32 = 6x + 9

Since the x's cancel out and leave an impossible statement -32 = 9, there is no solution.