How would I work this out I don’t understand it:( Watch
1) you now that you are looking for 3 separate 2 digit numbers, because of the first line, you can remember these as X, Y and Z
2) because of the line 'the first number is between 10 and 20' you know that 10 < x < 20
3)because of the line ' the second number is 3 times the first' you know that Y = 3x
4)because of the line 'the second number is 5 times the first' you know Z = 5x
5) Using this I wrote out all the numbers X could be ( 11-19 )
6) then crossed out 11 because the last line says all the numbers in the code are different, and 11 has 1 repeated twice
7) i then wrote next to this all of the numbers that could be Y, and once again crossed out a potential code if a number was repeated
8) I then did the same for Z, once again crossing out all potential codes with repeated numbers
9) this left a code where x = 18, y = 54 and z = 90
10) I have attached my working out below if you want to see the table described, which has the codes that don't work with the reasons they don't underlined in red.
I hope this helps you, message if there is anything you don't understand !