SOLUTION: how many 2 digit numbers are possible such that the sum of their digits is equal to twice the difference between digits?

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Question 1036845: how many 2 digit numbers are possible such that the sum of their digits is equal to twice the difference between digits?
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
The sum can't be odd, because then it wouldn't be divisible by 2.
Therefore, only even digits or odd digits are allowed.
11,13,15,17,19--13 works and 31
20,22,24,26,28----26 works and 62
31,33,35,37,39----39 works and 93
40,42,44,46,48--no
51,53,55,57,59--no
yx
y+x=2(y-x)
y+x=2y-2x
3x=y
========
y+x=2(x-y)
y+x=2x-2y
x=3y
6 numbers are possible