B

Adam went to a shop where he bought $7$ buns and $2$ cakes for $64$ Kč. Mirek bought $5$ buns, $3$ cakes and $4$ rolls for $79$ Kč. Petra went to the same shop as Adam and Mirek and bought $5$ buns and $4$ rolls. Since it was only $20$ minutes to closing, she got a discount for each piece of bakery goods worth $1$ Kč and so she paid $37$ Kč. Which of the following statements about the prices of goods before the discount is the only incorrect?

Let $[x,y,z]$ be the solution of the system of $3$ equations with $3$ unknowns represented by the matrix $$\left(\begin{array}{cccc}1& 2& 1& 6\\ 2& -1& 1& 1\\ -1& 1& 1& 2\end{array}\right).$$ Which of the components $x$, $y$, and $z$ is of the highest value?

The sweet shop offers $3$ types of confections in various packages. The price of each package can be seen below the package (as shown in the picture). How much would the sample package cost if it contained $1$ piece of each type of confection?

People in Kocourkov pay by coins named groschen. Their coins are worth $1$, $5$ or $7$ groschen. Martin and Petr, who live in Kocourkov, emptied their saving boxes and started counting their saved coins. They found out that Petr had $6$ pieces of each type of a coin more than Martin, who had $40$ coins in total. They were surprised to find out that Martin has the same number of $1$-groschen and $7$-groschen coins in total as Petr has of $5$-groschen ones. Petr was proud to have $78$ groschen more than Martin, who was only $2$ short of having $200$ groschen. Which of the following systems can be used to find out how many coins of each type both boys have?