SOLUTION: I am 6 years older than my sister. my brother is 6 years older than i am. the sum of our ages is 72 years. how old is my sister

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: I am 6 years older than my sister. my brother is 6 years older than i am. the sum of our ages is 72 years. how old is my sister       Log On


   

Question 1105954: I am 6 years older than my sister. my brother is 6 years older than i am. the sum of our ages is 72 years. how old is my sister
Found 3 solutions by josgarithmetic, ikleyn, greenestamps:
Answer by josgarithmetic(39620) About Me  (Show Source):
Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
.
My age + my brother age + my sister age = 72


  x    + (x+6)          + (x-6)         = 72


==================>  3x = 72  ====>  x = 72%2F3 = 24.


Answer.  My sister is 18 years old.


Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


You are 6 years older than your sister and 6 years younger than your brother.
That means your age is the average of the three ages.
If the sum of the three ages is 72, then the average age is 72/3 = 24.
So your age is 24; that means your sister's age is 18.