"My dream is to be a conceptual airplane designer"
There are many reputable websites to help students improve their math skills. Some sites provide diagnostic tests to help determine your strengths and weaknesses. Other sites provide tutorials, examples, and even videos. Search the web using the topic you are studying and be prepared to find a lot of helpful sites. Here are some links you may find useful:
You may find many other websites offering valuable and more thorough information than the websites just provided. Search the web. Here is a list of topics you may want to search: