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Answer:
- X = Y -9
- Y = Z +7
- X +Y = 25
Explanation:
We can let X, Y, and Z represent the ages of Xavier, Yolanda, and Zed, respectively.
1) X = Y -9 . . . . . . Xavier is 9 years younger than Yolanda
2) Y = Z +7 . . . . . Yolanda is 7 years older than Zed
3) X +Y = 25 . . . . the sum of ages of Xavier and Yolanda is 25
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Additional comment
The first equation can be substituted into the last to give 2Y-9=25 ⇒ Y=17. The other ages are easily computed once you know this. X=8, Z=10.