[tex]1)x - x \times 10\% = {}^{10)} x - \frac{10x {}^{(10} }{100} = \frac{10x - x}{10} = \frac{9x}{10} [/tex]
[tex]2) \frac{9x}{10} - \frac{9x}{10} \times 10\% = \frac{ {}^{10)} 9x}{10} - \frac{9x {}^{} }{10} \times \frac{10 {}^{(10} }{100} = \frac{90x - 9x}{100} = \frac{81x}{100} \\ [/tex]
[tex] \frac{81x}{100} = 1620 \\ [/tex]
81x = 1620 x 100
81x = 162000
x = 162000 : 81
x = 2000 lei ✔