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Bill, Phil, and Jenny are siblings. Bill is twice as old as Phil. Jenny is two years younger than Bill. Currently, their dad is twice as old as the sum of their ages. In nine years, Dad's new age will be equal to the sum of his three kids' new ages. What is Jenny's current age?

 Nov 20, 2017
 #1
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Let Phil's age =P
Bill's age =2P
Jenny's age =2P - 2
[P + 2P + 2P - 2] x 2 =D
[P + 2P + 2P - 2] +27 =D+9, solve for D, P
P = 4 years - Phil's age
2*4 =8 years - Bills's age
8 - 2 =6 years- Jenny's current age.
D =36 years - Dad's age.
18+27 =36 + 9
45 Years = 45 yeas - nine years from now.

 Nov 20, 2017
edited by Guest  Nov 20, 2017
 #2
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2/b=p

b-2=j

p+b+j=2d

b+p+j=18

3p+2p-2=18 or 5p=20

20/5=4

Penny is 4 years old.

 Nov 20, 2017
 #3
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Mmm seems to be some disagreement here ://

 

Bill, Phil, and Jenny are siblings.

Bill is twice as old as Phil.                         2P=B    

Jenny is two years younger than Bill.        B-2=J        B=J+2

so     

B=2P=J+2 

2P=J+2

J=2P-2 

 

Currently, their dad is twice as old as the sum of their ages.  D=2(P+B+J)

 

In nine years, Dad's new age will be equal to the sum of his three kids' new ages.

D+9= P+B+J+27

D= P+B+J+18

But    D=2(P+B+J)

therefore Dad is 36

P+B+J=18

P+2P+(2P-2)=18

5P-2=18

P=4     Phil is 4

Bill is 8

Jenny is  6

 

 

check:

Bill 8,  Phil 4 , and Jenny 6  are siblings.    Dad is 36

Bill is twice as old as Phil.    yes

Jenny is two years younger than Bill.    yes

Currently, their dad is twice as old as the sum of their ages.   2*(8+4+6)=36    yes

In nine years, Dad's new age will be equal to the sum of his three kids' new ages. What is Jenny's current age?       45=18+27    yes

 Nov 20, 2017

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