a: \(7+\left(\dfrac{7}{12}-\dfrac{1}{2}+3\right)-\left(\dfrac{1}{12}+5\right)\)
\(=7+\dfrac{7}{12}-\dfrac{1}{12}-\dfrac{1}{2}+3-5\)
\(=7+1-2\)
=6
c) \(1-\left\{1:\left[2^3+1-\left(-\dfrac{1}{2}\right)^2\right]\right\}\)\(=1-\left[1:\left(8+1-\dfrac{1}{4}\right)\right]=1-\left(1:\dfrac{35}{4}\right)=1-\dfrac{4}{35}\)\(=\dfrac{35-4}{35}=\dfrac{31}{35}\)