Please explain this. thank you

Below

Step-by-step explanation:

We can just plug in 3 for k and solve :

     x - 1 / 3 = 3

Step 1. Multiply both sides by 3

     x - 1 = 9

Step 2. Move the -1 to the other side and change the sign

     x = 9 + 1

     x = 10

We can check to see if this works :

     10 - 1 / 3 = k

     9 / 3 = k

           3 = k so this is correct

Hope this helps!

what is the original number? you forgot to add it.

there are infinitely many solutions.