x-suma
Prima zi : [tex] \frac{x}{4} [/tex]
A doua zi : [tex] \frac{60}{100} * \frac{x}{4}[/tex] = [tex] \frac{60x}{400}= \frac{3x}{20[tex] \frac{3x}{20} [/tex]} [/tex]
A treia zi : 150
x-[tex] \frac{x}{4} [/tex]-[tex] \frac{3x}{20} [/tex]=150
x(1-1/4-3/20) = 150