x-pretul initial
x-[tex] \frac{30}{100} [/tex]·x=1,40
simplifici [tex] \frac{30}{100} [/tex] cu 10 si avem:
x-[tex] \frac{3x}{10} [/tex]·x=1,40
aducem la acelasi numitor⇒[tex] \frac{10x-3x}{10} [/tex]=1,40
[tex] \frac{7x}{10} [/tex]=1,40⇒x=[tex] \frac{1,40*10}{7} [/tex]
x=2 lei-pretul initial