Solution:Ratio of the investment of A, B and C
= 3500 × 12 : 2100 × 12 : 4000 × x
= 105 : 63 : 10x
Profit share of A = Rs. 3000
Profit share of B = 3000 × 63/105 = Rs. 1800
Profit share of C = 6800 − 3000 − 1800
= Rs. 2000
10x = 63 × 2000 / 1800
x = 7