document.write( "Question 338583: mike's age is 3/4 of mary's age. In 5 years, Mike's age will be 7/9 mary's age, how old is mike now? \n" ); document.write( "

Algebra.Com's Answer #242738 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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let m = Mary's present age
\n" ); document.write( "let k = Mike's present age
\n" ); document.write( ":
\n" ); document.write( "Write an equation for each statement:
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\n" ); document.write( "Mike's age is 3/4 of Mary's age.
\n" ); document.write( "k = $\"3%2F4\"$ m
\n" ); document.write( "we can handle this as a decimal
\n" ); document.write( "k = .75m
\n" ); document.write( ":
\n" ); document.write( "In 5 years, Mike's age will be 7/9 Mary's age,
\n" ); document.write( "k + 5 = $\"7%2F9\"$ (m+5)
\n" ); document.write( "Multiply both sides by 9
\n" ); document.write( "9(k+5) = 7(m + 5)
\n" ); document.write( "9k + 45 = 7m + 35
\n" ); document.write( "9k = 7m + 35 - 45
\n" ); document.write( "9k = 7m - 10
\n" ); document.write( "Replace k with .75m
\n" ); document.write( "9(.75m) = 7m - 10
\n" ); document.write( "6.75m = 7m - 10
\n" ); document.write( "6.75m - 7m = -10
\n" ); document.write( "-.25m = -10
\n" ); document.write( "m = $\"%28-10%29%2F%28-.25%29\"$
\n" ); document.write( "m = +40 is Mary's present age
\n" ); document.write( "then
\n" ); document.write( "k = .75(40)
\n" ); document.write( "k = 30 is Mike's present age
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check our solutions in the statement:
\n" ); document.write( "\"In 5 years, Mike's age will be 7/9 Mary's age\"
\n" ); document.write( "30 + 5 = $\"7%2F9\"$ (40+5)
\n" ); document.write( "35 = $\"7%2F9\"$ (45)
\n" ); document.write( "35 = 7*5 \r
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