x - cena mleka
y - cena rogalika
\left \{ {{4x+14y=11} \atop {2x+6y=5}} \right.
\left \{ {{4x=11-14y} \atop {2x+6y=5}} \right.
\left \{ {{x=\frac{11-14y}{4}} \atop {2x+6y=5}} \right.
\left \{ {{x=\frac{11-14y}{4}} \atop {2(\frac{11-14y}{4})+6y=5}} \right.
\left \{ {{x=\frac{11-14y}{4}} \atop {2(\frac{11-14y}{4})+6y=5}} \right.
\left \{ {{x=\frac{11-14y}{4}} \atop {(\frac{11-14y}{2})+6y=5}} \right.
\left \{ {{x=\frac{11-14y}{4}} \atop {(11-14y+12y=10}} \right.
\left \{ {{x=\frac{11-14y}{4}} \atop {(-2y=-1}} \right.
\left \{ {{x=\frac{11-14y}{4}} \atop {(y=0,5}} \right.
\left \{ {{x=\frac{11-14*0,5}{4}} \atop {(y=0,5}} \right.
\left \{ {{x=1} \atop {(y=0,5}} \right.
mleko - 1zł
rogal - 0,5zł
(1+0,5)*31=46,5zł
pytanie tylko czy np. w niedzielę też były robione zakupy…