A' s 1 day's work = 1/8
B' s 1 day's work = 1/10
∴ A' s share : B' s share
= 1/8 : 1/10 = 5/40 : 4/40 = 5 : 4
Let A' s share = 5k
and B' s share = 4k.
According to the question,
5k + 4k = 900
⇒ 9k = 900
∴ k = 100
∴ A' s share = 5k = 5 x 100 = ₹ 500
and B' s share = 4k = 4 x 100 = ₹ 400.