If each digit has to be 1 or 2 and they have to add up to 3, there are only a few ways we can have this number. The first is 111 (1+1+1 = 3), the second is 21 (2+1 = 3), and finally the third is 12 (1+2 = 3). your final answer is 111,21, and 12 hope this helps!
