\(500-\left\{5.\left[409-\left(8+3+21\right)^2+100\right]\right\}:15\)
\(500-\left[5.\left(409-32^2+100\right)\right]:15\)
\(500-\left[5.\left(409-1024+100\right)\right]:15\)
\(500-\left(5.-515\right):15\)
\(500+2575:15\)
\(500+\dfrac{515}{3}\)
\(\dfrac{1500}{3}+\dfrac{515}{3}=\dfrac{2015}{3}\)