Answered

the sum of Kris and Victor's ages is 27 years.  in 3 years, victor will be twice as old as Kris will be.  what are their present ages?



Answer :

let k=kris and victor =v
k+v=27
in  3 years, victor will be twice as old as kris will be.so
v+3=2(k+3)
v=2k+6-3
v=2k+3
so (2k+3)+k=27
3k=24
k=8          27-8=19
kris is 8 years now.   victor is 19 years old. 
LET KRIS'S AGE BE X YEARS AND VICTOR'S AGE BE Y YEARS
GIVEN, X + Y = 27 ------------EQ 1
IN THREE YEARS,
KRIS WILL BE X+3 YEARS AND VICTOR WILL BE Y+3 YEARS
GIVEN , Y+3 = 2(X +3 )
Y+3 = 2X+ 6
Y - 2X =6-3
Y - 2X =3 ------------EQ 2
FROM EQ 1 WE GET,
X =27 -Y
SUBSTITUTING THE VALUE OF X IN EQ 2 ,WE GET
Y - 2(27 -Y) =3
Y - 54 +2Y =3
3Y-54 =3
3Y =57
Y=57/3 =19
PUTTING THE VALUE OF Y IN EQ 1 
X +19 =27
X =27-19=8
THEREFORE, KRIS IS 8 YEARS OLD AND VICTOR IS19 YEARS OLD