Answer:
Rs. 4266.67(approx) will be paid for gazing 20 cows for 8 weeks.
Explanation:
A shepherd is paid rs. 2400 for gazing 18 cows for 5 weeks .
⇒ Number of money paid for gazing 1 cow for 1 week is, 
then,
for gazing 20 cows for 8 weeks is= Rs.
Therefore, the amount paid for gazing 20 cows for 8 weeks is,
or Rs. 4266.67(approx)
The coefficient of b is h/2. Multiply the equation by the reciprocal of that.
(2/h)A = (2/h)·(h/2)·b
b = 2A/h . . . . . simplify