The following facts are known about the ages of A, B & C:
 You can get A's age by transposing the two digits of B's age.
 B is 10 times as old as C.
 Twice C's age equals the difference between the ages of A and B.
How old is the youngest?
Let B=10x+y with x and y integers.
Then the problem conditions can be expressed in terms of x and y.
A=10y+x
C=x+y/10
2(x+y/10)=9y9x
From the last equation, x=(4/5)y. Integral x requires y=5 so x=4.
Then the ages are A=54, B=45, C=4.5.

Posted by xdog
on 20171226 09:08:31 