--> Let Anshu takes x Days , than Atul takes (2*(4/5)x) = 8x/5 Days.
--> Together Atul and Anshu takes = 16 Days . So, Together 1 Day work = 1 / 16 .
--> Taking 1(one) Day work of , Anshu + Atul = Together .
--> (1 / x) + (5 / 8x) = 1 / 16 , Solving x = (16*13) / 8 = 26 Days [Anshu].