Question 394149
In the year 2000 Donald was 12 and his father was 40. 
In which year was Donald's father 8 times as old as Donald?
<pre><font face = "batangche" color = "indigo" size = 4><b>

Let the desired year be x years before 2000 or the year 2000-x.

x years before 2000 Donald was 12-x and his father was 40-x.

So we want 12-x to be {{{1/8}}}th of 40-x.  To say that in algebra,

          12 - x = {{{1/8}}}(40 - x)

Clear of fractions by multiplying both siades by 8

         96 - 8x = 8*{{{1/8}}}(40 - x)

Cancel the 8 and the {{{1/8}}} and you have

         96 - 8x = 40 - x
             -7x = -56
               x = 8

So the year was 2000-x or 2000-8 or 1992, when Donald was 4 and his
father was 32.

Edwin</pre>