SOLUTION: The sum of the ages of three sisters is 78 years. The second sister is eighteen years less than twice the first sister's age. The third sister is eight years older than the first s

Question 1058227: The sum of the ages of three sisters is 78 years. The second sister is eighteen years less than twice the first sister's age. The third sister is eight years older than the first sister. How old are the sisters?
Found 2 solutions by josmiceli, MathTherapy:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let the sister's age be
, , and
--------------------------
(1)
(2)
(3)
--------------------------
Substitute (2) and (3) into (1)
(1)
(1)
(1)
(1)
(1)
------------------
(2)
(2)
(2)
(2)
-------------------
(3)
(3)
(3)
-------------------
The sisters are 22, 26, and 30
----------------------------
check:
(1)
(1)
(1)
OK

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

The sum of the ages of three sisters is 78 years. The second sister is eighteen years less than twice the first sister's age. The third sister is eight years older than the first sister. How old are the sisters?

Let the 1st sister's age be F
Then 2nd sister's age is: 2F - 18
And, the 3rd sister's age = F + 8
Since their ages sum to 78, we get: F + 2F - 18 + F + 8 = 78
4F - 10 = 78
4F = 88
F, or 1st sister's age is:

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