document.write( "Question 935623: The average age of a grandmother, a grandfather, and 7 grandchildren is 28. The average age of 7 grandchildren is 15 years. How old is the grandfather, if he is 3 years older than the grandmother? \n" ); document.write( "

Algebra.Com's Answer #568865 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
1. $\"%28GM%2BGP%2BGK%29%2F9=28\"$
\n" ); document.write( "2. $\"GK%2F7=15\"$
\n" ); document.write( "3. $\"GP=GM%2B3\"$
\n" ); document.write( "From eq. 2,
\n" ); document.write( " $\"GK=105\"$
\n" ); document.write( "Substitute this and eq. 3 into eq. 1,
\n" ); document.write( " $\"%28GM%2BGM%2B3%2B105%29%2F9=28\"$
\n" ); document.write( " $\"2GM%2B108=252\"$
\n" ); document.write( " $\"2GM=144\"$
\n" ); document.write( " $\"GM=72\"$
\n" ); document.write( "So then,
\n" ); document.write( " $\"GP=72%2B3\"$
\n" ); document.write( " $\"GP=75\"$ \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );