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Mr and Mrs. Wilson have 3 children: Jessica, Jeremy, and Jenna. The average of Jessica and Jeremy's age is $ 11$. The average of all three children's ages is $ 10$. How old is Jenna?

 Feb 25, 2021
 #1
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Let's label the children's ages:

 

Jessica = a

Jeremy = b

Jenna = c

 

(a + b)/2 = 11 

 

(a + b + c)/3 = 10

 

From there, we can simplify:

 

a + b = 22          . (1)

a + b + c = 30     . (2)

 

Subtract equation (1) from (2) to get c = 8.

 Feb 25, 2021

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