1) A=\(\frac{\left(19+1\right)\left(\left(19-1\right):2+1\right):2}{\left(39+1\right)\left(\left(39-21\right):2+1\right):2}\)
A=\(\frac{20.10:2}{40.10:2}\)
=> A=\(\frac{1}{2}\)
2) \(5^{x+x+1+x+2}=10^{18}:2^{18}\)
\(\Rightarrow5^{3x+3}=5^{18}\)
\(\Rightarrow3x+3=18\)
\(\Rightarrow3\left(x+1\right)=18\)
\(\Rightarrow x+1=18:3=6\)
\(\Rightarrow x=6-1=5\)