Question

A two digit number is seven times the suum of its digits.thr number formed by reversing the digiys is 18 less than the given number.find the given number

Answer 1

Let the unit digit be x and ten's digit be y.
Number = 10y + x.
As per the question,
7(x+y) = 10y + x
=> 7x +7y = 10y + x
=> 6x = 3y
=> 2x = y.
Now, By reversing the digits, Number = 10x +y
Again, as per the question,
10y + x -18 = 10x +y
9y - 9x = 18
y - x = 2
and, we know , y = 2x
So, 2x -x = 2 => x = 2.
and, y = 2*2 = 4.
Thus, Given number = 42.