\(\left\{210:\left[16+3.\left(6+3.22\right)\right]\right\}-3\)
\(=\left\{210:\left[16+3.\left(6+66\right)\right]\right\}-3\)
\(=\left\{210:\left[16+3.72\right]\right\}-3\)
\(=\left\{210:\left[16+216\right]\right\}-3\)
\(=\left\{210:232\right\}-3\)
\(=\dfrac{105}{116}-3\)
\(=\dfrac{-243}{116}\)