the sum of 4 times a girls age and 7 times a boys age is 169. the boy is one year older than twice the age of the girl. find out how old they will be in ten years

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asked Sep 24, 2016 127k views

2 votes

the sum of 4 times a girls age and 7 times a boys age is 169. the boy is one year older than twice the age of the girl. find out how old they will be in ten years

Mathematics
middle-school

Andrew Hoos asked

by Andrew Hoos

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1 Answer

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$x-\ girl's\ age\ \\y-\ boy's\ age\\\\ 4x+7y=169\\\\ 2x+1=y\\\\ \\\\ 4x+7*(2x+1)=169\\\\ 4x+14x+7=169\ \ \ | subtract\ 7\\\\ 18x=162\ \ \ | divide\ by\ 18\\\\ x=9\\\\ y=2*9+1=18+1=19\\\\ In\ ten\ years\ they\ will\ be:\\ girls:\ 19\\boys:\ 29.$