A's 1 day's work = \( \Large \frac{1}{3} \)

B's 1 day's work = \( \Large \frac{1}{4} \)

A's share : B's share = \( \Large \frac{1}{3} \) : \( \Large \frac{1}{4} \)

= \( \Large \frac{4}{12} \) \( \Large \frac{3}{12} \) = 4 : 3

A's share = \( \Large \frac{4}{7} \times 2800 \) 

= \( \Large 4 \times 400 \) = Rs.1600