Use the digits 0-9 only once each, so that each expression has the same value

As you can read below, we can write expressions for addition and subtraction, but not for multiplication and division.

Step-by-step explanation:

We can find out examples for addition and subtraction, this way:

1. Addition:

1 + 8 = 9    1 + 7 = 8     1 + 6 = 7   1 + 5 = 6   1 + 4 = 5

2 + 7 = 9    2 + 6 = 8   2 + 5 = 7  2 + 4 = 6  2 + 3 = 5

3 + 6 = 9    3 + 5 = 8   3 + 4 = 7

4 + 5 = 9

2. Subtraction:

9 - 1 = 8   9 - 2 = 7  9 - 3 = 6   9 - 4 = 5

               8 - 1 = 7   8 - 2 = 6   8 - 3 = 5

                               7 - 1 = 6    7 - 2 = 5

                                                6 - 1 = 5  

For multiplication and division we inevitably will repeat any of the digits, like these examples:                                            

8 * 1 = 8 (8 is repeated and therefore not a valid example)

4 * 2 = 8

9 ÷ 3 = 3 (3 is repeated and therefore not a valid example)

3 ÷ 1 = 3 (3 is repeated and therefore not a valid example)