document.write( "Question 135953: Mike's age is three fourths of Mary's age. In 5 years Mike's age will be seven ninths Mary's age. How old is Mike now? Please help with this problem. \n" ); document.write( "

Algebra.Com's Answer #99617 by ptaylor(2198) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let x=Mary's age; x+5=Mary's age in five years
\n" ); document.write( "And let y=Mike's age; y+5=Mike's age in 5 years\r
\n" ); document.write( "\n" ); document.write( "Now we are told the following:
\n" ); document.write( "y=(3/4)x---------------------------------eq1
\n" ); document.write( "and
\n" ); document.write( "(y+5)=(7/9)(x+5) multiply each side by 9
\n" ); document.write( "9y+45=7x+35-------------------------------------eq2\r
\n" ); document.write( "\n" ); document.write( "substitute y=(3/4)x from eq1 into eq2 and we get:\r
\n" ); document.write( "\n" ); document.write( "9(3/4)x+45=7x+35 or
\n" ); document.write( "(27/4)x+45=7x+35 subtract 45 and also 7x from each side
\n" ); document.write( "(27/4)x-7x+45-45=7x-7x+35-45 collect like terms\r
\n" ); document.write( "\n" ); document.write( "(27/4)x-(28/4)x=-10
\n" ); document.write( "-x/4=-10 multiply each side by -4
\n" ); document.write( "x=40----------------------------------Mary's age now\r
\n" ); document.write( "\n" ); document.write( "(3/4)x=(3/4)*40=30---------------------Mike's age now\r
\n" ); document.write( "\n" ); document.write( "CK
\n" ); document.write( "30+5=(7/9)(40+5)
\n" ); document.write( "35=(7/9)*45
\n" ); document.write( "35=35\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor
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