x=suma initiala
In prima zi: 0,4 × x
a doua zi:
[tex](x - 0.4 \times x) \times \frac{1}{3} [/tex]
60+prima zi+a doua zi=x
[tex]60 + \frac{4}{10} \times x + (x - \frac{4}{10} \times x) \times \frac{1}{3} = x \\ 60 + \frac{4x}{10} + \frac{10x - 4x}{10} \times \frac{1}{3} = x \\ 60 + \frac{4x}{10} + \frac{6x}{30} = x \\ \frac{60 \times 30}{30} + \frac{4x \times 3}{30} + \frac{6x}{30} = \frac{30x}{30} \\ 1800 + 12x + 6x = 30x \\ 1800 + 18x = 30x \\ 12x = 180 0\\ x = \frac{1800}{12} \\ x = 150[/tex]
