SOLUTION: Jenny is twice as old as Jimmy. Jesse is 10 years older then jimmy. If the sum of their ages is 90, how old is Jenny?

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Question 774394: Jenny is twice as old as Jimmy. Jesse is 10 years older then jimmy. If the sum of their ages is 90, how old is Jenny?
Found 2 solutions by lwsshak3, DrBeeee:
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Jenny is twice as old as Jimmy. Jesse is 10 years older then jimmy. If the sum of their ages is 90, how old is Jenny?
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let x=Jimmy's present age
2x=Jenny's present age
x+10=Jesse's present age
x+2x+x+10=90
4x=80
x=20
2x=40
how old is Jenny? 40

Answer by DrBeeee(684) About Me  (Show Source):
You can put this solution on YOUR website!
To avoid all the J's,
Let a = Jenny's age
Let b = Jimmy's age
Let c = Jesse's age
REM: when you have 3 unknowns, you need 3 equations!
The problem statement provides us with the following three equations.
(1) a = 2*b,
(2) c = 10 + b, and
(3) a + b + c = 90
Put (1) and (2) into (3) to get
(4) 2*b + b + 10 +b = 90 or
(5) 4*b = 90 - 10 or
(6) 4*b = 80 or
(7) b = 20
From (1) we get
(8) a = 2*20 or
(9) a = 40
And from (2) we get
(10) c 10 + 20 or
(11) c = 30
Let's check our ages with (3).
Is (40 + 20 + 30 = 90)?
Is (90 = 90)? Yes
Answer: Jenny is 40 years of age.