maths
posted by xavier .
John is 3 times as old as Susan now. In 4 years time John will be 18 years older than Susan. Find John's age and Susan;s age now.

present ages:
Susan  x
John  3x
Four years from now:
Susan  x+4
John  3x + 4
3x+4 = x+4 + 18
2x = 18
x = 9
Susan is now 9 and John is now 27
check:
in four years:
Susan = 13, John is 31
is 31 greater than 13 by 18 ? YES!!