Question 355609
let the digit in tens place be x
& in the units place be y
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10y+x=10x+y+36
9y-9x=36
/9
y-x=4.....................1
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x+y=3(x-y)
x+y=3x-3y
2x-4y=0
/2
x-2y=0....................2

Add equation1 & 2
-y=4
y=-4
plug value of y in 1
y-x=4
-4-x=4
x=-8

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-84 is the number
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m.ananth@hotmail.ca