<PRE><B>Question 972459</B>
A man is thirty years old, and his son is thirteen years old.
 How many years will the son be three-fourths as old as his father?
:
let y = no. of years for this to be true
y + 13 = {{{3/4}}}(y+30)
multiply both sides by 4
4(y+13) = 3(y+30)
4y + 52 = 3y + 90
4y - 3y = 90 - 52
y = 38 yrs for this to happen
:
:
Check this out, find their ages in 38 yrs.
13 + 38 = 51
30 + 38 = 68
:
51/68 = .75 which is 3/4</PRE>