# Task № 2.1

Condition:

Dmitry has socks in his wardrobe: 6 pairs of blue socks, 18 pairs of black socks, and 12 pairs of white socks. Dmitry bought some more pairs of black socks and found that now the black socks make up 3/5 of the total number of socks. How many pairs of black socks did Dmitry buy?
Answer: 9

Exact match of the answer -1 point

## Solution.

Dmitry had an equal number of pairs of black and all other pairs of socks, and after the purchase, it turned out that the black pairs make up three parts of all socks, while the other pairs make up two parts. This means that Dmitry bought half of the number of pairs of black socks he already had, that is, 9 pairs.

## Condition:

Dmitry has socks in his wardrobe: 16 pairs of blue, 20 pairs of black, and 4 pairs of white. Dmitry bought several more pairs of black socks and found that now the black socks make up $2 / 3$ of the total number of socks. How many pairs of black socks did Dmitry buy?

Answer: 20

Exact match of the answer -1 point

Solution by analogy with task №2.1.

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