$\sqrt{11-2√30}$ - $\sqrt{13-√42}$ - $\sqrt{7}$
=$\sqrt{(√6-√5)²} - $\sqrt{(√7-√6)²}$ - $\sqrt{7}$
= l$\sqrt{6} $- $\sqrt{5}$l - l$\sqrt{7}$ - $\sqrt{6}$l - $\sqrt{7}$
= $\sqrt{6}$ - $\sqrt{5}$ - $\sqrt{7}$ + $\sqrt{6}$ - $\sqrt{7}$
= `2`$\sqrt{6}$ - $\sqrt{5}$ - `2`$\sqrt{7}$