Czech crowns

Small Petra saves money. Grandfather gives her ten crowns. Petra asked his older sister to let her calculate how much he had saved. Sister told her that he had less than 30 crowns. If the sum is divided by three, leave one crown. Suppose the sum is divided by the five left with her two. How much has Petra saved up?

Correct answer:

x =  22 Kč

Step-by-step explanation:

10 Kč: 10 = 3 × 3 + 1;     10 = 2 × 5 + 0

11 Kč: 11 = 3 × 3 + 2;     11 = 2 × 5 + 1

12 Kč: 12 = 4 × 3 + 0;     12 = 2 × 5 + 2

13 Kč: 13 = 4 × 3 + 1;     13 = 2 × 5 + 3

14 Kč: 14 = 4 × 3 + 2;     14 = 2 × 5 + 4

15 Kč: 15 = 5 × 3 + 0;     15 = 3 × 5 + 0

16 Kč: 16 = 5 × 3 + 1;     16 = 3 × 5 + 1

17 Kč: 17 = 5 × 3 + 2;     17 = 3 × 5 + 2

18 Kč: 18 = 6 × 3 + 0;     18 = 3 × 5 + 3

19 Kč: 19 = 6 × 3 + 1;     19 = 3 × 5 + 4

20 Kč: 20 = 6 × 3 + 2;     20 = 4 × 5 + 0

21 Kč: 21 = 7 × 3 + 0;     21 = 4 × 5 + 1

22 Kč: 22 = 7 × 3 + 1;     22 = 4 × 5 + 2 ⇐⇐⇐⇐

23 Kč: 23 = 7 × 3 + 2;     23 = 4 × 5 + 3

24 Kč: 24 = 8 × 3 + 0;     24 = 4 × 5 + 4

25 Kč: 25 = 8 × 3 + 1;     25 = 5 × 5 + 0

26 Kč: 26 = 8 × 3 + 2;     26 = 5 × 5 + 1

27 Kč: 27 = 9 × 3 + 0;     27 = 5 × 5 + 2

28 Kč: 28 = 9 × 3 + 1;     28 = 5 × 5 + 3

29 Kč: 29 = 9 × 3 + 2;     29 = 5 × 5 + 4

30 Kč: 30 = 10 × 3 + 0;     30 = 6 × 5 + 0



Try another example


Did you find an error or inaccuracy? Feel free to write us. Thank you!







You need to know the following knowledge to solve this word math problem:

Units of physical quantities:

Grade of the word problem:

Related math problems and questions: