document.write( "Question 935502: The mean of the ages of father and his son is 27 years. After 18 years, father will be twice as old as his son. Their present ages are \n" ); document.write( "

Algebra.Com's Answer #568727 by Horlaye(27) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let the father and son's age be represented by x and y respectively
\n" ); document.write( " From the 1st sentence
\n" ); document.write( " (x+y)/2 = 27
\n" ); document.write( " Cross multiply the equation
\n" ); document.write( " x+y = 2*27
\n" ); document.write( " x+y = 54..........(1)
\n" ); document.write( " From the 2nd sentence
\n" ); document.write( " x+18 = 2(y+18)
\n" ); document.write( " x+18 = 2y+36
\n" ); document.write( " x-2y = 36-18
\n" ); document.write( " x-2y = 18..........(2)
\n" ); document.write( " Bring the two equations together
\n" ); document.write( " x+y = 54..........(3)
\n" ); document.write( " x-2y = 18..........(4)
\n" ); document.write( " Eliminate equation (4) from equation (3)
\n" ); document.write( " 3y = 36
\n" ); document.write( " y = 36/3
\n" ); document.write( " y = 12
\n" ); document.write( " Substitute y = 12 in equation (3)
\n" ); document.write( " x+y = 54
\n" ); document.write( " x+12 = 54
\n" ); document.write( " x = 54-12
\n" ); document.write( " x = 42
\n" ); document.write( " Therefore there present ages =
\n" ); document.write( " Father = x = 42
\n" ); document.write( " Son = y = 12 \n" ); document.write( "

\n" );