Question

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

Answer 1

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

$={\{3-4\}}^{-1}$

$={(-1)}^{-1}$

$=-1.$

Hence, the answer is $-1.$