## Task 3 - 250513

Three customers in a hardware store bought screws. Each screw cost 7 pfennigs. The second customer bought four more screws than the first customer. The third customer bought twice as many screws as the second customer. The three customers paid a total of 5 marks and 32 pfennigs.

How much did the third customer pay?
If the first customer bought $x$ screws, then the second customer bought $x+4$ screws, and the third customer bought $2 \cdot (x+4)$ screws. This means $2 \cdot (x+4) = 2x + 8$.

Adding these three quantities, we get $x + x + 4 + 2x + 8 = 4x + 12$, so the three customers bought a total of $4x + 12$ screws.

Since they paid a total of 5.32 M and each screw cost 7 Pfennig, they bought a total of $532 \div 7 = 76$ screws. Therefore, $4x + 12 = 76$, and thus $x = 16$.

The first customer bought 16 screws, the second bought 4 more, so 20 screws, and the third bought twice as many, so 40 screws. Since $40 \cdot 7 = 280$, he paid $2.80 \text{M}$ for them.