X is a two – digit number, if it is known that its unit’s digit exceeds its ten’s digit by 2 and that the product of the given number and the sum of its digits is equal to 144. Then the number is:
24
{ Let the ten's digits be x. Then, unit's digit = x+2
Number = 10x+(x+2)=11x+2;Sumofdigits=x+(x+2)=2x+2. ∴(11x+2)(2x+2)=144⇔22x2+26x−140=0⇔11x2+13x−70=0 ⇔(x−2)(11x+85)=0⇔x=2. Hence, required number = 11x + 2 = 24