Question 636506
three years ago, Rica was thrice as old as Dandy. Three years hence, she will be twice as old. find their present ages.
ans:-
let Dandy is x yrs now ,so 3 yrs ago he was x-3 yrs
so rica was 3(x-3)yrs then
3yrs hence dandy will be x+3 & rica will be 3(x-3)+6
as per question 3(x-3)+6=2(x+3)
or 3x-9+6=2x+6
or x=9= dandy;s age now
& rica is 3(9-3)+3=21 yrs ans

otherwise
let dandy is x yrs & rics is y yrs now 
three years ago y-3=3(x-3)
or 3x-y=6----------1
Three years hence y+3=2(x+3)
or 2x-y=-3 --------2
subtracting (2) from(1)
x=9
from (1) y=21 ans