Question

Solve:
i) 10% of x=$20$
ii) x-30% of x=$35$

Answer 1

We have,

$10$ of $x=20$

$\frac{10}{100}\times x=20$

$\frac{1}{10}\times x=20$

$x=200$

Hence, the value of x is 200.

Similarly,

$x-30$ of $x=35$

$\frac{x-30}{100}\times x=35$

$x^2-30x=3500$

$x^2-30x-3500=0$

We know that

$x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

Therefore,

$x=\frac{30\pm \sqrt{900-4\times 1\times -3500}}{2}$

$x=\frac{30\pm \sqrt{900+14000}}{2}$

$x=\frac{30\pm \sqrt{14900}}{2}$

$x=\frac{30\pm 10\sqrt{149}}{2}$

$x=15\pm 5\sqrt{149}$

Hence, the value of $x$ is $15\pm 5\sqrt{149}$.