Jill made 20 muffins. She put them into 3 boxes and has two muffins left. Hoa many are in each box if they all contain the same amount

Question

1. have To create a equation that matches the problem 
2. then create a sequence and undo chart 
3. replace variable with answer 

Answer 1

20 = 3x + 2

then create a sequence and undo chart

I don't know what this means.  Sorry

20 = 3x + 2

18 = 3x

6 = x