document.write( "Question 150712: BOB'S FATHER AGE IS 3 TIMES OLD AS BOB.4 YEARS AGO,HE WAS 4 TIMES OLDER.HOW OLD IS BOB? \n" ); document.write( "

Algebra.Com's Answer #110656 by Fombitz(32388) $\"\"$ $\"About$

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B - Bob's age
\n" ); document.write( "F- Bob's father's age
\n" ); document.write( "1. $\"F=3B\"$
\n" ); document.write( "Four years ago, Bob was B-4 years old and his father was F-4.
\n" ); document.write( "2. $\"F-4=4%28B-4%29\"$
\n" ); document.write( "Now you have two equations with two unknowns, you can solve it.
\n" ); document.write( "Substitute eq. 1 into eq. 2 and solve for B.
\n" ); document.write( "2. $\"F-4=4%28B-4%29\"$
\n" ); document.write( " $\"3B-4=4%28B-4%29\"$
\n" ); document.write( " $\"3B-4=4B-16\"$
\n" ); document.write( " $\"-B=-12\"$
\n" ); document.write( " $\"B=12\"$
\n" ); document.write( "Now use equation 1 to solve for F.
\n" ); document.write( "1. $\"F=3B\"$
\n" ); document.write( " $\"F=3%2812%29\"$
\n" ); document.write( " $\"F=36\"$
\n" ); document.write( "Bob is 12 and his father is 36.
\n" ); document.write( "Four years ago, Bob was 8 and his father was 32. \n" ); document.write( "

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