Question 1045363
Helen was 13 years old on her birthday and 
<pre>
Everything is in months in this problem.
There are 12 months in a year.

So Helen is 13x12 = 156 months old.
</pre>
the average age of her four friends was 12 years 2 months. 
<pre>
That's 12x12+2 = 144+2 = 146 months.

So the sum of the 4 friends ages in months is 4x146 = 584 months.
</pre>
If the average age of all six children was 11 years 5 months. 
<pre>
That's 12x11+5 = 132+5 = 137 months.

So the sum of the 6 children's ages in months is 6x137 = 822 months.

{{{(matrix(6,1,"Helen's","age,",which,is,156,months))}}}{{{""+""}}}{{{(matrix(8,1,"Paul's","age,",which,we,let,be,N,months))}}}{{{""+""}}}{{{(matrix(9,1,Sum,of,four,"friend's","ages,",which,is,584,months))}}}  {{{""=""}}} {{{(matrix(2,1,822,months))}}}

{{{156+N+584}}}{{{""=""}}}{{{822}}}

{{{N+740}}}{{{""=""}}}{{{822}}}

{{{N}}}{{{""=""}}}{{{82}}}
                                      <u>  6</u>
So Paul is 82 months old, which is  12)82 
                                       <u>72</u>
                                       10

6 years and 10 months.

Edwin</pre>