a) \(\sqrt{16}.\sqrt{25}+\sqrt{196}:\sqrt{49}\)
\(=4.5+14:7\)
\(=20+2=22\)
b) \(36:\sqrt{2.3^2.18}-\sqrt{169}\)
\(=36:\sqrt{18^2}-13\)
\(=36:18-13\)
\(=2-13=-11\)
c) \(\sqrt{\sqrt{81}}\) d) \(\sqrt{3^2}+4^2\)
\(=\sqrt{\sqrt{9^{^2}}}\) \(=3+16\)
\(=\sqrt{9}\) \(=19\)