Notăm:
s - prețul stiloului;
c = prețul creionului.
s - c = 30 ⇒ s = c+30
c < s de 5 ori ⇒ s > c de 5 ori ⇒ s = 5c
[tex]\it c\ \ |\rule{30}{0.8}|\\ \\ s\ \ |\rule{30}{0.8}|\rule{0.2}{0.2}\ \ \ \ \ \ \ \ \ \ \ \ \ \ +30\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\\ \\ s\ \ |\rule{30}{0.8}|\rule{30}{0.8}|\rule{30}{0.8}|\rule{30}{0.8}|\rule{30}{0.8}|\\ \\ 4c=30 \Rightarrow c=30:4=7,50\ \ell ei\\ \\ s=7,50+30=37,50\ \ell ei[/tex]
