This is a good problem to work out mentally...



But since this is algebra.com, here is an algebraic method:

A = Alex's age



(A) + (A+5) + (A-10) = 55

3A - 5 = 55

3A = 60

A = 20   --->  A-10 = 10  (Fiona is 10)





Check:

Spelling out all the ages:

Alex is    20

Fiona is   10

Natasha is 25

--------------

Total is   55  (ok)



 

Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!
 

Natasha is 5 years older than Alex. Fiona is 10 years younger than Alex. If the total of their ages is 55, how old is the youngest of them?

It should be obvious to anyone who reads this that Fiona is the youngest.

Let Fiona's age be F

Then Alex' is F + 10, and Natasha's is: F + 10 + 5, or F + 15

We then get: F + F + 10 + F + 15 = 55

3F = 30

F, or Fiona, being the youngest is:  

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