A, B and C can do a piece of work in 15, 20 and 30 days. They undertake to complete the work for Rs. 810. How much share of A exceeds that of B ?

** Option:**

**A.**Rs. 90

**B.**Rs. 180

**C.**Rs. 270

**D.**Rs. 360

**Answer: A . Rs. 90**

** Justification:**

A's 1 day's work = $1/50$

B's 1 day's work = $1/20$

C's 1 days's work = $1/30$

Ratio of their shares = $ 1/15:1/20:1/30$ = 4 : 3 : 2

Thus, A's share in Rs. 810

=Rs. $4/9$ x 810 = Rs. 360

and, B's share in Rs. 810.

=Rs. $3/9$ x 810 = Rs. 270

Hence, difference between their shares = Rs. (360 - 270) = Rs. 90.