Question

un telefon s-a ieftinit de 2 ori cu 10% si costa 1620 lei.cat a costat inainte?​

Answer 1

Salut!

Răspuns: 2000 lei ✅

$1)x - x \times 10\% = {}^{10)} x - \frac{10x {}^{(10} }{100} = \frac{10x - x}{10} = \frac{9x}{10}$

$2) \frac{9x}{10} - \frac{9x}{10} \times 10\% = \frac{ {}^{10)} 9x}{10} - \frac{9x {}^{} }{10} \times \frac{10 {}^{(10} }{100} = \frac{90x - 9x}{100} = \frac{81x}{100}$

$\frac{81x}{100} = 1620$

81x = 1620 x 100

81x = 162000

x = 162000 : 81

x = 2000 lei ✔