I am a firm believer of the idea that mathematics is the most important school subject. Simply put, I feel that studying mathematics makes you an overall smarter person, even in other study areas. Studying mathematics develops critical thinking and problem solving skills that can be applied to other areas of life and other school subjects. As a part of everyday life we run into problems that need to be solved and although it might not seem like it, mathematics help us solve these everyday problems. When a person reaches a certain level of mathematical understanding they begin to apply these understanding to real life subconsciously, without realizing that mathematics is to thank for their heightened ability to come up with solutions and think in a way that people who do not prioritize math are able to do.
Here is a link to a website that posted an article about why mathematics is so important: http://www.mathworksheetscenter.com/mathtips/mathissoimportant.html
This article gives examples of what I was previously talking about, math makes you a generally smarter person. It provides scenarios in which math is necessary to get by and makes it easier to understand how a person with skills in mathematics would be able to get by these scenarios in a more efficient way than a person who lacked these same mathematical skills.