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?

wiseowl Feb 25, 2021

#1**+1 **

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.**

CubeyThePenguin Feb 25, 2021