The sum of the digits of a two-digit number is 9 less than the number. Which of the following digits is at ten's place of the number ?
Let say, the number is 'ab'.
So, $$ab=10a+b.$$
According to question,Â
$$a+b=10a+b-9.$$
or, $$a=1.$$
So, digit in ten's place is 1.
D is correct choice.
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