Question 422697
let m = the man's present age
let s = son's age
;
a man nine times as old as his son.
m = 9s
:
 In nine years, he will be only three times as old as his son.
m + 9 = 3(s + 3)
m + 9 = 3s + 27
m = 3s + 27 - 9
m = 3s + 18
Replace m with 9s (from the 1st equation)
9s = 3s + 18
9s - 3s = 18
6s = 18
s = {{{18/6}}}
s = 3 yrs is son's age
then
m = 9(3)
m = 27 yrs is the man's age
:
How old are each now?  3 and 27
:
I'll let you check to see if this is true, replace s and m with 3 and 27 in
the equations