If it’s only math and reading could it be dyslexia? Not that adhd is not a possibility but, I did struggle with math as a kid but, I was never unable to count to 20 and explain photosynthesis. It was more like, it took me longer to do math and I made more little mistakes like subtracting instead of adding, couldn’t focus on it and couldn’t/wouldn’t memorize times tables, but I could count higher than most other students. So I just wonder for the disparity to be that big between subjects perhaps there’s something that affects those specific subjects. Ofc it’s possible counting didn’t interest her like it interested me, I think I was trying to see how high numbers go, looking for the edge of infinity or something lol.