SOLUTION: Alex is 15 years older than Cristina. In 4 years, the sum of their ages will be 91. How old are they now?

Question 1126967: Alex is 15 years older than Cristina. In 4 years, the sum of their ages will be 91. How old are they now?
Answer by ikleyn(52787) (Show Source): You can put this solution on YOUR website!
.

A = C + 15            (1)    ("Alex is 15 years older than Cristina.")
(A+4) + (C+4) = 91    (2)    ("In 4 years, the sum of their ages will be 91")


Substitute expression A = C+15  from eq(1) into eq(2). You will get


((C+15)+4) + (C+4) = 91


2C + 15 + 4 + 4 = 91

2C = 91 - 15 - 4 - 4 = 68  ====>

C = 68/2 = 34.


Answer.  C is 34 years old.  A is 34+15 = 49 years old.  


Check.   (34+4) + (49+4) = 38 + 53 = 91.   ! Correct !

Solved.

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