I really don't understand math anymore

Hannah just got a very high score on her math "end-of-unit assessment". As I've explained before, Massachusetts teaches a very interesting version of math. You can no longer just say 2+2=4. You now have to explain why 2+2=4.

So here is how Hannah scored a 4 on her assessment (A 4 is the highest you can get and is very rarely given out):

QUESTION: On Monday there was a bicycle race in the park. There were 25 children and 18 adults in the race. How many people were in the race? Solve the problem. Show your work.

HANNAH'S ANSWER:

25-5=20
18-8=10
20+10=30
8+5=13
13+30=43
(therefore)
25+18=43

The rest of the answer I couldn't even follow at all so I can't even write it here for you but needless to say it received a "Very Organized!", "Great!", and a "Wow!" from her teacher.