@shashank_prabhulet 2 numbers are 'ab' and 'cd', such that ab>cd.abcd-(ab-cd)=5481100 * ab+cd-ab+cd=548199 * ab+2 * cd=5481
99*ab and 5481 are multiples of 9, hence cd must be a multiple of 9.
At cd=18, we get ab=55
Sum of the two 2-digit numbers= 55+18=73

@Rowdy-Rathore
F(x) = x^4-360x^2+400F(x) = (x^2+20)^2 - 400x^2F(x) = (x^2-20x+20)(x^2+20x+20) = Prime NumberSince the value of second factor is always positive and greater than 1 therefore, 1st factor hasto be equals to 1.x^2-20x+20 = 1x^2-20x+19= 0On solving,x = 1, 19.Putting back the values in the original equation we get f(x) = 41 and f(x) = 761.
So, the sum will be 41+761 = 802