document.write( "Question 868596: A girl is half the age of her mum and her dad is 5 years ahead of her mum. If you add up their ages you get 100. What is the age of each one of them? \n" ); document.write( "

Algebra.Com's Answer #523680 by JLJL(8) $\"\"$ $\"About$

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Let the girl's age = X
\n" ); document.write( "Let the mum's age = Y
\n" ); document.write( "Let the dad's age = Z\r
\n" ); document.write( "\n" ); document.write( "If the girl is half the age of her mum, then X = 1/2Y
\n" ); document.write( "If the dad is 5 years ahead of the mum, then Z = Y + 5
\n" ); document.write( "If the sum of age of all three people is 100, then X + Y + Z = 100\r
\n" ); document.write( "\n" ); document.write( "We can now replace X and Y in terms of Z.
\n" ); document.write( "Thus,
\n" ); document.write( "X + Y + Z = 100
\n" ); document.write( "1/2Y + Y + (Y + 5) = 100
\n" ); document.write( "1/2 Y + 2Y + 5 = 100
\n" ); document.write( "5/2Y + 5 = 100
\n" ); document.write( "5Y + 10 = 200
\n" ); document.write( "5Y = 200 - 10
\n" ); document.write( "5Y = 190
\n" ); document.write( "Y = 190/5
\n" ); document.write( "Y = 38\r
\n" ); document.write( "\n" ); document.write( "Substitute Y = 38 into X, then X = 1/2(38) = 19
\n" ); document.write( "Substitute Y = 38 into Z, then Z = 38 + 5 = 43\r
\n" ); document.write( "\n" ); document.write( "Conclusion: The girl's age is 19, the mum's age is 38 whereas the dad's age is 43 respectively. \n" ); document.write( "

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