a: \(P=\left(\dfrac{13}{84}\cdot\dfrac{7}{5}-\dfrac{5}{2}\cdot\dfrac{7}{180}\right):\dfrac{43}{18}+\dfrac{9}{2}\cdot\dfrac{1}{10}\)
\(=\dfrac{43}{360}\cdot\dfrac{18}{48}+\dfrac{9}{20}=\dfrac{1}{20}+\dfrac{9}{20}=\dfrac{10}{20}=\dfrac{1}{2}\)
b: \(A=\dfrac{1+0.4\cdot1000}{100\cdot1000\cdot10}=\dfrac{1+400}{1000000}=\dfrac{401}{1000000}\)