Question

Find a number such that if 5, 15 and 35 are added to it, the product of the first and third results may be equal to the square of the second.

Answer 1

let the number be  =  X

       ( 5 + X )  * ( 35 + X) = (15 + X)²

         175 + 40 X + X² = 225 + 30 X + X²

               10 X = 50
                                   X = 5

Answer 2

Let the no be x
so the nos be
X+5,X+15,X+35
ATQ,
(x+5)(x+35)=(x+15)²
⇒x²+40x+175=x²+30x+225
⇒10x=50
⇒x=5