What software can understand the following task: "A big cat needs 4 days to catch all the mice and a small cat needs 12 days. How many days need the both if they catch mice together?"?
Well this is a relatively new problem very tied to Question Answering. One of the recent systems is EUCLID that can answer those type of question the public Dolphin algebra question set by using a tree transducer cascade approach.
This paper details the proposed model Hopkins, M., Petrescu-Prahova, C., Levin, R., Le Bras, R., Herrasti, A., & Joshi, V. (2017). Beyond sentential semantic parsing: Tackling the math sat with a cascade of tree transducers. In Proceedings of the 2017 Conference on Empirical Methods in Natural Language Processing (pp. 795-804).
In the same sense, SEMEVAL has released a task related to Math QA, you can see the related bibliography and referenced works semeval 2019 task 10 internal.
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There was a lot of work on this topic through at UT Austin, which has now migrated to the Alan Institute.
There is no off-the-shelf software that will answer your question (if there was, DARPA would stop funding its development!), but you can read about the latest development in a number of recent papers.
This paper (Seo et al. EMNLP 2015) discusses the techniques that are used to interpret diagrams that accompany geometry problems, while this one (Hosseini et al. EMNLP 2014) talks about how to automatically parse verbs to interpret the meaning of a question. The 2015 TACL paper (Koncel-Kedziorski et al. 2015) completes this by discussing how to extract the relevant equations from a word problem. Once you have the equations, know what question is being asked, and can interpret any diagrams, you can do most high school math problems.
However, I don't think this is yet a fully reliable system. It is one part of a larger, long running effort to create a program that can achieve higher education certifications in many subjects. You can see many projects related to this at the Alan Institute's website.