Question 1027198: If (Mr. X + Mrs. Y = 69 years) and (Mr. X + Mr. Z = 72 years) and (Mrs. Y + Mr. Z = 79 years).
So, how old are Mr. X, Mrs. Y and Mr. Z?
Found 2 solutions by ikleyn, MathTherapy:
Answer by ikleyn(52802)   (Show Source):
You can put this solution on YOUR website! .
If (Mr. X + Mrs. Y = 69 years) and (Mr. X + Mr. Z = 72 years) and (Mrs. Y + Mr. Z = 79 years).
So, how old are Mr. X, Mrs. Y and Mr. Z?
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X + Y = 69, (1)
X + Z = 72, (2)
Y + Z = 79. (3)
Add the equations (1), (2) and (3). You will get
2X + 2Y + 2Z = 69 + 72 + 79 = 220,
or
X + Y + Z = 110. (4)
Now distract (1) from (4). You will get
Z = 110 - 69 = 41.
Now distract (2) from (4). You will get
Y = 110 - 72 = 38.
Now distract (3) from (4). You will get
X = 110 - 79 = 31.
Answer. X = 31, Y = 38, Z = 41.
For similar problems, see the lesson The tricks to solve some word problems with three and more unknowns using mental math in this site.
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website!
If (Mr. X + Mrs. Y = 69 years) and (Mr. X + Mr. Z = 72 years) and (Mrs. Y + Mr. Z = 79 years).
So, how old are Mr. X, Mrs. Y and Mr. Z?
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