To simplify this expression, follow the order of operations (PEMDAS/BODMAS):

First, perform the division: 45150 ÷ 75 = 602

Next, multiply:
306 × 602 = 184212
37095 × 9 = 333555

Substitute these values back into the expression:
500418 - (184212 + 333555) - 345 × 7

Now, continue with the addition inside the parentheses:
500418 - (517767) - 345 × 7

Next, multiply:
345 × 7 = 2415

Substitute this value back into the expression:
500418 - 517767 - 2415

Now, subtract:
500418 - 517767 - 2415
= -19364

Therefore, the simplified expression is -19364.