The sum of the present ages of a father and his son is 99 years. When the father was old as his son is now, his agewas four times age of the son at that time. The ratio of the present ages of the son and and the father is:(a) 3:7(b) 3 : 8(c) 4:9(d) 4:7

The sum of the present ages of a father and his son is 99 years. When

1.	The sum of the present ages of a father and his son is 99 years. When the father was old as his son is now, his agewas four times age of the son at that time. The ratio of the present ages of the son and and the father is:(a) 3:7(b) 3 : 8(c) 4:9(d) 4:7
Answer» f+s=99so s=99-fnow suppose x years ago f-x=99-f so 2f=99+x so f=(99+x)/2so f-x=4(s-x)(99+x)/2=4s-4x99+x=8s-8x99=8(99-f)-9x=99(8)-4(2f)-9x9x-4(99+x)=7(99)9x-4(99)-4x=7(99)so x=27so f=(99+27)/2=126/2=63so s=99-63=36so ration of son to father = 36/63=4:7