1) If you're a lemon, you're sour.
2) You're sour, If you're a lemon.
3) If you're not a lemon, you're not sour.
4) You're not sour, If you're not a lemon.
The only statements that are true are 1 and 2. 3 and 4 are not true because if you're not a lemon, you could still be sour and you could still be sour if you're not a lemon.

One reason that I love math, is that learning it in High School is very helpful for your future. Many jobs across America require for you to have some knowledge in math. So in other words, if you have good math skills you could have a lot of possible job openings in the future for very good pay. For example, Albert Einstein was so good at math that his theories and methods are still used today. So keep studying and doing your homework because maybe you'll be the next Einstein!