Question

x% of x is x-16
then, find the value of x.

(don't give irrelevant answer give full solution.)​

Answer 1

$\rm{}x\% \: \: \: of \: \: \: x \: \: \: is \: \: \: (x - 16)$

Here,

$\bf \frac{x}{100} \times x = x - 16 \\ \\ \tt\frac{ {x}^{2} }{100} = x - 16 \\ \\ \tt {x}^{2} = 100(x - 16) \\ \tt{x}^{2} = 100x - 1600 \\ \tt{ {x}^{2} - 100x + 1600 } = 0 \\ \tt{} {x}^{2} - 80x - 20x + 1600 = 0\\ \tt{}x(x - 80) - 20(x - 80) = 0\\ \sf{}(x - 80)(x - 20) = 0$

Therefore,

$\huge{ \sf{}x = \red{ 80} \: \: \: or \: \: \: \red{20}}$

Answer 2

Answer:

20 or 80

Step-by-step explanation:

(x-16)/x=x/100

= (x−16)*(100)=x^2

= 100x−1600=x2

= 100x−1600−x2=x2−x2

= −x2+100x−1600=0

= (−x+20)(x−80)=0 ( quadratic formula )

So x=20 or 80 because any number multiply by 0 is 0

can't really explain how the quadratic formula works, can someone help on this ?