http://www.actstudent.org/testprep/descriptions/mathcontent.html
There is the different parts that make up the mathematics ACT. According to this, there is around 9 problems that have to do with Algebra II (intermediate algebra). Even if you didn’t know any of these 9 problems, it is unlikely that you would miss all of them because you would probably be able to figure basic ones out or even just guess correctly on some. However, if you missed all 9 of them for some reason and got every other question right, that would still put you at a 30. Math test scoring often fluxuates between tests, but that’s a pretty solid estimate, and you can read more about it here.
http://blog.prepscholar.com/act-score-chart-raw-score-to-scaled-conversion
I hope that’s a helpful answer! That being said, I have to say that taking Algebra II did help me because not only do you learn basic skills that you will see on the ACT but it solidifies your knowledge of simple Algebra I concepts that will come up. The math is my least favorite section for sure but it’s definitely manageable. 