When A and B work together they take 20 days to complete the piece of work. When A works alone he takes 28 days. B gets a share of Rs. 600 when they work together. What is the total amount they receive?
1). Rs. 1,500
2). Rs. 1,600
3). Rs. 1,800
4). Rs. 2,100
A’s one day’s work $(= \frac{1}{{28}})$
A and B’s one day’s work $(= \frac{1}{{20}})$
B’s one day’s work $(= \frac{1}{{20}} - \frac{1}{{28}} = \frac{1}{{70}})$
(A’s one day’s work) ? (B’s one day’s work) $(= \frac{1}{{28}}:\frac{1}{{70}} = 5:2)$
B’s share is Rs. 600
Let 5x, 2x be A and B’s share.
∴ 2x = 600
∴ x = 300
A’s share = 5x = Rs. 1,500
Total share = 1500 + 600 = Rs. 2,100