Hi, I've studied mathematics at high school and I will start university next year. I'm worried about my mathematical knowledge in general. There are many "gaps" which lead to confusion. To give you some examples: 1) I've difficulty understanding why, for instance, 5 - (-2) = 5 + 2. The only explanation I have is: 5 - (-2) = 5 + -1*(-1*2) = 5 + (-1*-1)*2 = 5+2. 2) I can't really intuitively understand implicit differentiation. 3) I've difficulty grasping the basic counting principle, etc... I need a book which starts from the very bottom (covering many topics) and explains why some rules are the way they are. I'm thinking to buy Finite Math and Applied Calculus by Stefan Waner and Steven Costenoble. What's your opinion about the book? Can you recommend me other books? Thanks for reading.