To simplify the expression, we need to perform the operations inside the parentheses first:

-15/12 + 6/11 - 68/49

To add or subtract fractions, we need a common denominator. The least common multiple of 12, 11, and 49 is 12 * 11 * 49 = 6468.

-15/12 + 6/11 - 68/49 = (-15/12) * (539/539) + (6/11) * (588/588) - (68/49) * (132/132)
= -8070/6468 + 3528/6468 - 8976/6468
= (-8070 + 3528 - 8976)/6468
= -13518/6468

Now, let's simplify the expression outside the parentheses:

-1/4 + 7/33 - 5/3

To add or subtract fractions, we need a common denominator. The least common multiple of 4, 33, and 3 is 4 * 33 * 3 = 396.

-1/4 + 7/33 - 5/3 = (-1/4) * (99/99) + (7/33) * (12/12) - (5/3) * (132/132)
= -99/396 + 84/396 - 660/396
= (-99 + 84 - 660)/396
= -675/396

Finally, let's subtract the expression inside the parentheses from the expression outside the parentheses:

-675/396 - (-13518/6468)

To subtract fractions, we need a common denominator. The least common multiple of 396 and 6468 is 396 * 6468 = 2570208.

-675/396 - (-13518/6468) = (-675/396) * (6468/6468) - (-13518/6468) * (396/396)
= -4322700/2570208 + 536712/2570208
= (-4322700 + 536712)/2570208
= -3785988/2570208

Therefore, -1/4 + 7/33 - 5/3 - (-15/12 + 6/11 - 68/49) simplifies to -3785988/2570208.