How do I compute positive and negative numbers together?

One way we can think of positive and negative numbers is good guys and bad guys. Good guys are positive numbers and bad guys are negative numbers. When we add or subtract them we can imagine them meeting in an alley. After everyone pairs up to fight, the guys left over are the winners or result!

Why do we need standard deviations?

Standard deviations are useful to help us determine placement of a subject, even if the data collection was different. For example, ACT scores range in the 20's while SAT scores are in the thousands. In order for a college to compare two students from each test they can compare the standard scores that will be in the same context rather than the raw test scores.

When will I use this in my everyday life?

Not all of us will use every math topic everyday. Some will use Math more as they go on to programming or engineering jobs. Some may even use math in their construction work or running businesses. No matter where we are at, we will be problem solving everyday. We can learn how to navigate those problems the same way we learn to navigate math problems. We learn how to think logically through situations that may arise in our lives. Math is helping become wiser consumers and more logical human beings.