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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 sun of their ages. In nine years, their dad's age will be equal to the sum of his three kids' ages at that time. What is Jenny's
current age?

Respuesta :

Answer:

as below

Step-by-step explanation:

current ages

Bill is 8

Jenny is 6

and Phil is 4

the dad is  36

sqdancefan

9514 1404 393

Answer:

  6

Step-by-step explanation:

Let p, b, j, d represent the ages of Phil, Bill, Jenny, and Dad. We are given the relations ...

  b = 2p

  j = b -2

  2(p +b +j) = d

  (p+9) +(b+9) +(j+9) = d+9

_____

Solving the last equation for d, we get ...

  (p +b +j) +18 = d

Substituting for the sum of p, b, j in the third equation, we have ...

  2(d -18) = d

  d = 36 . . . . . . . . add 36-d

Substituting for b and j in the third equation, we get ...

  2(p +(2p) +(2p-2)) = 36 . . . . .  uses b=2p in the 2nd equation

  10p -4 = 36 . . . . . . . . . . . . . . . collect terms

  p = 40/10 = 4 . . . . . . add 4; divide by 10

  b = 2p = 8

  j = b -2 = 6

Jenny's current age is 6.

_____

All of the ages are ...

  Bill: 8; Jenny: 6; Phil: 4; Dad: 36

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