SOLUTION: This year, Jake is 5 years older than his sister. Three years ago, Jake was twice his sister's age. How old is Jake's sister?

Question 795430: This year, Jake is 5 years older than his sister. Three years ago, Jake was twice his sister's age. How old is Jake's sister?
Answer by DrBeeee(684) (Show Source): You can put this solution on YOUR website!
Let j = Jake's current age
Let s = his sisters current age
The first statement gives us
(1) j = s + 5
The second statement about 3 years ago we have
(2) j = 2*s, but this is 3 years ago , so we have
(3) j-3 = 2*(s-3) OK? or
(4) j = 2*s -6 +3 or
(5) j = 2*s -3
Now solve (1) and (5) simultaneously.
Since j = j we can set (1) = (5) to get
(6) s + 5 = 2*s - 3 or
(7) s = 8
From (1) we get
(8) j = 8 + 5 or
(9) j = 13
Let's check this using (3).
Is (13 - 3 = 2*(8 - 3))?
Is (10 = 2*5)?
Is (10 = 10)? Yes
Answer: This year Jake's sister is 8 years old.
RELATED QUESTIONS
this year, jake is 5 years older than his sister. three years ago, jake was twice his... (answered by josgarithmetic,Theo)

jake is 5 years older than his sister three years ago jake was twice his sisters age how... (answered by stanbon)

Jake is 8 times older than his older sister Lake. 29 Years ago, Jake was 5 times as old... (answered by ikleyn)

Five years ago, Jake's age was one less than half his age now. How old is Jake... (answered by josgarithmetic)

please help me with this age problem; Harry is one year older than twice his... (answered by stanbon)

Jake is five years older than laura. Four years ago jake was twice as old as laura was... (answered by lwsshak3)

Jerson is 12 years older than his sister Hershey. Two years ago, Jerson's age is twice as (answered by josgarithmetic)

Martin is 5 years older than his sister. Five years ago, he was 2 times older than his... (answered by Timnewman)

Robbie is four years older than his sister, Michela. seven years ago, Robbie was three... (answered by TimothyLamb)