\(A=\sqrt{75}-3\sqrt{63}-2\sqrt{27}+5\sqrt{28}\)
\(=5\sqrt{3}-9\sqrt{7}-6\sqrt{3}+10\sqrt{7}\)
\(=\sqrt{7}-\sqrt{3}\)
\(B=\sqrt{\left(3+2\sqrt{5}\right)^2}-\sqrt{\left(3-2\sqrt{5}\right)^2}\)
\(=3+2\sqrt{5}-\left|3-2\sqrt{5}\right|\)
\(=3+2\sqrt{5}-2\sqrt{5}+3\)
\(=6\)