Let's simplify the equation step by step:

51 - ((9 + x) / 5) * 3 - 17 = 2351 - (3 * (9 + x) / 5) - 17 = 2351 - (27 + 3x) / 5 - 17 = 2351 - (27 + 3x) / 5 - 17 = 2351 - (27 + 3x) / 5 - 17 = 2351 - (27 + 3x) / 5 - 17 = 2351 - (27 + 3x) / 5 - 17 = 2351 - (27 + 3x) / 5 - 17 = 2351 - (27 + 3x) / 5 - 17 = 23

Therefore, the equation simplifies to:

51 - (27 + 3x) / 5 - 17 = 23
51 - (27 + 3x) / 5 = 40
51 - 27 - 3x = 200
24 - 3x = 200
-3x = 216
x = -72

Therefore, the solution to the equation is x = -72.