I =
(500*9*6)/100 = 270

150 = (750*5*R)/100

R = 4%

70 = (P*4*7/2)/100

P = 500

160 = (180*4*R)/100

R = 5%

Let sum = x. Then, S.I. = 2x/5, Time = 10 years.Rate = (100 * 2x) / (x * 5 * 10) = 4%

Let sum = x. Then, S.I. = 0.125x = 1/8 x, R = 10%Time = (100 * x) / (x * 8 * 10) = 5/4 = 1 1/4 years.

Let sum = x. Then, amount = 7x/6S.I. = 7x/6 - x = x/6; Time = 3 years.Rate = (100 * x) / (x * 6 * 3) = 5 5/9 %.

Let the sum lent to C be Rs. x. Then,(2500 * 7 * 4) / 100 + (x * 7 * 4) / 100 = 11207/25 x = (1120 - 700) => x = 1500

Let the rate be R% p.a. Then,(5000 * R * 2)/100 + (3000 * R * 4)/100 = 2200100 R + 120 R = 2200R = 10%

Let the required ratio be x: 1: y. 
Then S.I on Rs x for 6 years at 10% p.a = S.I on re.1 10 years at 12 %p.a 
X × 10/100 × 6 = 1 × 12/100 × 10 
=> X = 120/60 =2 
S.I on Re.1 for 10 years at 12 % p.a = S. I on Rs. Y for 12 years at 15 % p.a 
Therefore, (1 x 12/100 x 10) = (y x 15/100 x 12) 
=> y = 120/180 = 2/3 
Required ratio = 2 : 1 = 2/3 = 6 : 3 : 2