Question

Evaluate

$-{\{{\left(\frac{1}{3}\right)}^{-1}-{\left(\frac{1}{4}\right)}^{-1}\}}^{-1}$

Answer 1

It can be written ${\{{\left(\frac{1}{3}\right)}^{-1}-{\left(\frac{1}{4}\right)}^{-1}\}}^{-1}$ as
$=-{\{\left(3\right)-\left(4\right)\}}^{-1}$
$=-{(-1)}^{-1}$
$=-(-1)$

$=1$