To solve this expression, we need to perform the operations in parentheses first, then multiplication and division from left to right, and finally addition and subtraction from left to right.

(19//20 + 1//2 + 4//5 + 3//4) = (0 + 0 + 0 + 0) = 0

Now the expression becomes:

0 * (-123) - (-5092) / 76

Now we perform multiplication and division:

0 * (-123) = 0

(-5092) / 76 = -67

Now the expression becomes:

0 - (-67)

Now we perform subtraction:

0 - (-67) = 0 + 67 = 67

Therefore, the final answer is 67.