Question 625310
Let the number "ab"

Reversed number = "ba"

a+b=10

10b+a = 2(10a+b)-1

10b+a = 20a+2b-1

10b+a -20a -2b +1 =0

-19a+8b+1=0

Since b = 10-a

-19a+8(10-a)+1=0

-19a+80-8a+1=0

-27a=-81

a = 3

b=7

Answer: original number is 37

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