x = 13
subtract x from both sides of the equation
6 = 2x - x - 7
6 = x - 7
add 7 to both sides
6 + 7 = x ⇒ x = 13
As a check
substitute this value into the equation and if both sides are equal then it is the solution
left side = 13 + 6 = 19
right side = (2 × 13) - 7 = 26 - 7 = 19
hence x = 13 is the solution