A. 5 : 7 : 8
B. 20 : 49 : 64
C. 38 : 28 : 21
D. 49 : 20 : 64
Let their investments be Rs. x for 14 months, Rs. y for 8 months and Rs. z for 7 months respectively
Then, 14x : 8y : 7z = 5 : 7 : 8
Now, 14x/8y = 5/7 <=> 98x = 40y <=> y = (49/20) x
and 14x/7z = 5/8 <=> 112x = 35z <=> z = (112/35) x = (16/5) x
=> x : y : z = x : (49/20) x : (16/5) x = 20 : 49 : 64