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Let E = 10a + b be Esher's age.
So, the number E has the tens digit "a" and the ones digit "b".
Let M be the Marta's age.
From the condition, we know that the Marta's age is M = 10b+a, the reversed number to the Esher's age.
We also are given that
M + 13 = 2*(E+13),
which implies
M = 2E + 13.
Using the decimal forms of the numbers E and M, it means that
10b + a = 20a + 2b + 13, or
8b - 19a = 13. (1)
So, from the condition, we have ONLY ONE equation for two unknown digits "a" and "b", equation (1).
But we also know that a" and "b" are INTEGER numbers between 1 and 9 each.
At this point, you can write b = and search for those integer "a" that produce integer values of "b".
It is easy to do in Excel.
In this way, I found a= 1, b= 4.
So, the Esther age is 14 years, while Marta's age is 41 years. ANSWER
You can check, on your own, that all requirements of the condition are satisfied.
Solved.