Answer:
A. 2
B. 8
C. 4
Step-by-step explanation:
Overall, you just make sure they all equal the same thing. Since 7+2+3=12, fit the blank so it also equals 12.
Same goes with B. 8+2=10, so fill in the blank to where it equals 10 (8). 0+4 is four, so not sure how you didn't get that haha.
Hope this helps :)