## Task 4 - 220524

A student buys 5 identical notebooks and 7 identical pencils, for which he pays $3.80 \mathrm{M}$ in total.

How much does such a notebook cost and how much does such a pencil cost, if a pencil costs twice as much as a notebook?
Due to $2 \cdot 7 + 5 = 19$, the 7 pencils and 5 notebooks cost the same as 19 notebooks. Because $380 : 19 = 20$, a notebook consequently costs $20 \text{Pf}$.

Because $2 \cdot 20 = 40$, a pencil therefore costs 40 Pf.

Solutions of the II. Round 1982 taken from [5]

### 2.24 XXIII. Olympiad 1983

### 2.24.1 I. Round 1983, Class 5