Question 1127562
(1)  J = C + 7   (from "7 years ago Jean was as old as Chinoso")
(2)  J + C = 29   (…"Jean and Chinoso's age add up to 29")<br>

Substitute for J:
(C+7) + C = 29
          2C = 22   —>  C = 11  —> J = 18
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Ans:  Chinoso is 11 and Jean is 18
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Check:  11+18 = 29
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Alternate (shorter) solution, using Jean's age (expressed in terms of C):
 C+7 = (29-C)   —>  2C = 22 —> C=11 —> J=18
  
…and using Chinoso's age (expressed in terms of J):
 J-7 = 29-J  —>  2J = 36 —>  J=18 —> C=11