{(1/3)-1 - (1/4)-1}-1 will be:

Concept: For any nonzero base a (including a fraction), raising it to the power -1 gives its reciprocal: a-1 = 1/a. For a fraction p/q, this means (p/q)-1 = q/p — the numerator and denominator swap.

1. Apply the reciprocal rule to each inner term: (1/3)-1 = 3 and (1/4)-1 = 4.

2. Substitute these into the braces and subtract in the order given: 3 - 4 = -1.

3. Apply the outer exponent -1 to this result: (-1)-1 = 1/(-1) = -1.

Cross-check: Only 1 and -1 are their own reciprocals among real numbers, so inverting -1 must return -1 again — this confirms the result independently of re-doing the arithmetic.

Hence, the value of the expression is -1.