5 persons share equally,so share of one person = 1/5
New share, 4 persons share equally,so share of one person = 1/4
Increase in the share= 1/5 - 1/4 = 1/20

Let, money invested by A, B and C are respectively x, 3x and 5x.
Required ratio of profit, A:B:C = 4*x+8*(x+x) : 4*3x+8*(3x/2) : 4*5x+8*(5x/2)
= 20x : 24x : 40x
= 5 : 6 : 10