Word Problems to 20 (Subtraction)

What are the ways to make 20 for addition and the ways to subtract 20? :

These are ways to minus twenty:
20-0=, 20-19=, 20-18=, 20-17=, 20-16=, 20-15=, 20 -14=, 20 -13=, 20-12=, 20-11= and 20-10=.

The addition number bonds to twenty:
0 + 20, 1 + 19,  2 + 18,  3 + 17,  4 + 16, 5 + 15,  6 + 14,  7 + 14,  8 + 12,  9 + 11 and 10+10.