SOLUTION: Carla is five years older than her sister Julie. The product of their ages is 234. How old is Julie?

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Question 1194063: Carla is five years older than her sister Julie. The product of their ages is 234. How old is Julie?
Found 3 solutions by Theo, josgarithmetic, MathTherapy:
Answer by Theo(13342)   (Show Source): You can put this solution on YOUR website!
c = carla's age.
j = julie's age.
c = j + 5
c * j = 234
replace c with j + 5 to get:
(j + 5) * j = 234
simplify to get:
j^2 + 5j = 234
subtract 234 from both sides to get:
j^2 + 5j - 234 = 0
factor this quadratic equation to get (j + 18) * (j-13) = 0
solve for j to get:
j = -18 or j = 13
j can't be negative, so j = 13
c = j + 5 = 18
carla is 18 years old
julie is 13.
13 * 18 = 234
solution is confirmed to be good.

Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!
j for Julie
j+5, for Carla


-----second sentence

Looking at factorizations,

13 corresponds to j.

Julie is 13 years of age.
Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!
Carla is five years older than her sister Julie. The product of their ages is 234. How old is Julie?
Unless requested to form an equation or equations, all you need to do is find 2 factors of 234 that differ by 5. 
These are 18 and 13, so the older, Carla, is 18, and the younger, Julie, is 13.
That's all!!

If you're having problems finding these factors, then forming a quadratic equation, and solving this quadratic,
using the quadratic equation formula, will be another "route" to take.
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