A certain number of two digits is three times the sum of its digits and if 45 be added to it, the degits are reversed. The number is.  Options:
A) 23 B) 27 C) 32 D) 72 E) 46
Let the ten's digit be x and unit's digit be y.   Then 10x + y = 3 (x+y) ==&gt; 7x - 2y = 0 ==&gt; 7x - 2y = 0----&gt; (I)   10 + y + 45 = 10y + x ==&gt; y - x = 5 ===&gt; -2x + 2y = 10------(II)   By adding (I) and (II) we get 5x = 10   so x = 2 and y = 7 so the required number is 27.   so the correct option is 27) 27.
<result>B</result>
A certain number of two digits is three times the sum of its digits and if 45 be added to it, the degits are reversed. The number is.