x- numărul
[tex] 10\% \times 2x + 25\% \times 3x = 38[/tex]
[tex]\frac{10}{100} \times 2x + \frac{25}{100} \times 3x = 38[/tex]
[tex]\frac{1}{10} \times 2x + \frac{1}{4} \times 3x = 38[/tex]
[tex]\frac{1}{5} \times x + \frac{3}{4} \times x = 38[/tex]
[tex] \frac{x}{5} + \frac{3x}{4} = 38[/tex]
numitor comun: 20
[tex] \frac{4x}{20} + \frac{15x}{20} = 38[/tex]
[tex] \frac{19x}{20} = 38[/tex]
[tex]19x = 38 \times 20[/tex]
[tex]19x = 760[/tex]
[tex]x = 760 \div 19[/tex]
[tex]x = 40[/tex]
Probă:
[tex]10\% \times 2 \times 40 + 25\% \times 3 \times 40 = [/tex]
[tex] = \frac{10}{100} \times 80 + \frac{25}{100} \times 120[/tex]
[tex] = 8 + \frac{1}{4} \times 120[/tex]
[tex] = 8 + 30[/tex]
[tex] = 38[/tex]
