A number consists of two digits. The sum of the digits is 9. If 63 is subtracted
from the number, its digits are interchanged. Find the number.  Choose the correct option.
A) 27 B) 36 C) 81 D) 72 E) 18
Let the ten's digit be x. Then, unit's digit = (9 - x).   Number = l0x + (9 - x) = 9x + 9.   Number obtained by reversing the digits = 10 (9 - x) + x = 90 - 9x.   therefore, (9x + 9) - 63 = 90 - 9x =&gt;	18x = 144 =&gt;	x = 8.   So, ten's digit = 8 and unit's digit = 1.   Hence, the required number is 81.   Answer is 81.
<result>C</result>
A number consists of two digits. The sum of the digits is 9. If 63 is subtracted
from the number, its digits are interchanged. Find the number.