Let the number of days to complete the work be N.
According to the question,
k/20 + (k - 2)/24 + (k - 5)/ 30 = 1
⇒ [6k + 5(k - 2) + 4(k - 5)] / 120 = 1
⇒ 6k + 5k + 4k = 120 + 10 + 20
⇒ 15k = 150
∴ k = 10
∴ Work done by A = 10/20 = 1/2
∴ Share of A from the assured money
= (1/2) x 5400
= ₹ 2700