SOLUTION: There are two brothers and two sisters. in 10 years they will total 100 in their ages. How much will the total be in 7 years? i'm still convinced it's 88..can someone explain why

Question 388958: There are two brothers and two sisters. in 10 years they will total 100 in their ages. How much will the total be in 7 years?
i'm still convinced it's 88..can someone explain why it isn't 88 ?
Found 3 solutions by richard1234, stanbon, jerryguo41:
Answer by richard1234(7193)   (Show Source): You can put this solution on YOUR website!
Let their current ages be a, b, c, d. We have (a+10) + (b+10) + (c+10) + (d+10) = 100 --> a + b + c + d = 60. In 7 years their total will be

(a+7) + (b+7) + (c+7) + (d+7) = a + b + c + d + 28 = 60 + 28 = 88...strange...
Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
There are two brothers and two sisters. in 10 years they will total 100 in their ages. How much will the total be in 7 years?
----
Let their ages now be b,B and s,S
---
Equations:
In 10 years:
b+10 + B+10 + s+10 + S+10 = 100
b+B+s+S = 60
-----------------------
In 7 years:
b+7+B+7+s+7+S+7 = ?
(b+B+s+S)+28 = ?
60+28 = ?
? = 88
===============
88 is correct
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Cheers,
Stan H.
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Answer by jerryguo41(197)   (Show Source): You can put this solution on YOUR website!
a,b,c,d = Siblings
------- Plus Ten due to "In ten years"

------- "plus 7 years"
---- a+b+c+d=40

So in 7 years their added ages will be 68
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