Given: Total number of eggs = 100 number of eggs left after giving 80% of good eggs = 36 Calculation: Let the number of rotten eggs be a. The total number of eggs is 100. Remaining good eggs = 100 – a Now, he gives 80% of the good eggs to his neighbors and he is left out with 36 eggs. ∴ 100 - 80% of (100 – a) = 36 ⇒ 100 – 80 + 0.8a = 36 ⇒ 20 + 0.8a = 36 ⇒ 0.8a = 16 ⇒ a = 20