document.write( "Question 118139: A wealthy old man is criticized for marrying a woman for he is three times her age. He wittily replies ,\"h, but in 20 years time 2 shall only be twice her age.\" How old is the man and his wife? \n" ); document.write( "
Algebra.Com's Answer #86243 by bucky(2189)![]() ![]() ![]() You can put this solution on YOUR website! Let W represent the wife's present age and M represent the man's present age. \n" ); document.write( ". \n" ); document.write( "At the present time the man is 3 times as old as his wife. So 3 times the wife's age equals the \n" ); document.write( "man's age. In equation form this is: \n" ); document.write( ". \n" ); document.write( "3W = M \n" ); document.write( ". \n" ); document.write( "20 years from now the wife will be W + 20 years old and the man will be M + 20 years old. \n" ); document.write( "You are told that at that time the man's age will equal twice that of his wife's age. In \n" ); document.write( "equation form this is: \n" ); document.write( ". \n" ); document.write( "2(W + 20) = M + 20 \n" ); document.write( ". \n" ); document.write( "Multiply out the left side of this second equation and you get: \n" ); document.write( ". \n" ); document.write( "2W + 40 = M + 20 \n" ); document.write( ". \n" ); document.write( "Get rid of the 40 on the left side by subtracting 40 from both sides to get: \n" ); document.write( ". \n" ); document.write( "2W = M - 20 \n" ); document.write( ". \n" ); document.write( "And get rid of the M on the right side by subtracting M from both sides. When you do that \n" ); document.write( "subtraction the equation becomes: \n" ); document.write( ". \n" ); document.write( "2W - M = -20 \n" ); document.write( ". \n" ); document.write( "But the very first equation told us that M = 3W. So in this latest equation we can substitute \n" ); document.write( "3W for M to get: \n" ); document.write( ". \n" ); document.write( "2W - 3W = -20 \n" ); document.write( ". \n" ); document.write( "Do the subtraction on the left side. 2W minus 3W equals -W so the equation becomes: \n" ); document.write( ". \n" ); document.write( "-W = -20 \n" ); document.write( ". \n" ); document.write( "Multiply both sides of this equation by -1 and it becomes: \n" ); document.write( ". \n" ); document.write( "W = 20 \n" ); document.write( ". \n" ); document.write( "Since W is the wife's current age, we know that at this time the wife is 20 years old. \n" ); document.write( "And since the man is presently 3 times as old as his wife, he has to be 60. \n" ); document.write( ". \n" ); document.write( "As a check, if the wife is currently 20, in 20 years from now she will be 40. And since \n" ); document.write( "the man is currently 60 years old, in 20 years he will be 80. At that time will he be \n" ); document.write( "twice as old as his wife ... is 80 twice as old as 40? Yes it is, so the answers check. \n" ); document.write( ". \n" ); document.write( "The wife is now 20 and her husband is 60. \n" ); document.write( ". \n" ); document.write( "Hope this helps you to understand the problem and how to solve it. \n" ); document.write( ". \n" ); document.write( "Have a happy new year! \n" ); document.write( ". \n" ); document.write( " |