a number consists of two digits whose sum is 9.if 9 is added to the number ,its digits are reversed .find the number Answer by checkley79(3341) (Show Source):
You can put this solution on YOUR website! 10x+y+9=10y+x
x+y=9 or x=9-y
10(9-y)+y+9=10y+(9-y)
90-10y+y+9=10y+9-y
-10y+y-10y+y=9-90-9
-18y=-90
y=-90/-18
y=5 ans. for the original units digit.
x=9-5
x=4 ans. for the tebns digit.
Proof:
45+9=54
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