document.write( "Question 575473: A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now? \n" ); document.write( "
Algebra.Com's Answer #369669 by ankor@dixie-net.com(22740)\"\" \"About 
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let g = daughter's present age
\n" ); document.write( "let b = brother's present age
\n" ); document.write( "let f = father's present age
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\n" ); document.write( "Write an equation for each statement:
\n" ); document.write( ":
\n" ); document.write( "\"A girl is twice as old as her brother
\n" ); document.write( "g = 2b
\n" ); document.write( "\" and half as old as her father.\"
\n" ); document.write( "g = .5f
\n" ); document.write( ":
\n" ); document.write( "\"In 50 years, her brother will be half as old as his father.\"
\n" ); document.write( "b + 50 = .5(f+50)
\n" ); document.write( "b + 50 = .5f + 25
\n" ); document.write( "b = .5f + 25 - 50
\n" ); document.write( "b = .5f - 25
\n" ); document.write( "We can replace .5f with g
\n" ); document.write( "b = g - 25
\n" ); document.write( "we can replace g with 2b
\n" ); document.write( "b = 2b - 25
\n" ); document.write( "25 = 2b - b
\n" ); document.write( "b = 25 is brothers age
\n" ); document.write( "then
\n" ); document.write( "2(25) = 50 yrs is the daughter's present age
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\n" ); document.write( ":
\n" ); document.write( "Check this using the third equation: that makes the father 100 yrs old
\n" ); document.write( "in 50 years: 25 + 50 = .5(100+50); checks out anyway\r
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