The investments of three partners are in an AP. Their venture makes an annual profit of Rs. 2100. What is the share of the partner who neither invested the most nor the least?
Let the investments be a - d, a and a + d. The sum of these investments = 3a. The share of the middle partner would be a/3a = (1/3)rd of the profit = $2100/3$ = Rs. 700.