X-rays are a **basic medical imaging technology**. They allow practitioners to *inspect internal organs* and body systems. X-rays can also be viewed as the little brother of ultrasounds.

X-rays are made by exposing a piece of paper or other material to an X-ray tube. The process is very careful, however, so most times it is not seen.

X-rays are a critical part of medicine, because they can help diagnose conditions and explain what **things look like**. They also have value as Gifts for Medical Professionals, since they can help them recognize conditions and **apply treatment tips** and strategies.

## Find y when x = -5

When x = -5, y = -15 is a very rare situation. Most times, when the value of an item is noted, it is as a fraction of 15.

However, this does not mean that an exception cannot be made for this value. It can!

When the item being valued is a member of the family known as the minus 5s, or if the item has some other exception to valuing such as specific rarity or historical significance. In these cases, there may be a *lower value required* to negate the value of the minus 5s on the piece.

For example, if a pendant has aminus 5s on it, then it would need to be worth less than its **equivalent standard pendant** with a plus sign. This **would prevent someone thinking** that they were getting a **plus (+/-) five piece** when in fact they were just getting one that was minus (-).

## Find z when x = 15 and y = 10

If you know the value of an item between y = 10 and y = 15, you can use this information to find the value of x in the equation X – Y = 30.

For example, if the value of an apple is 6, you can figure out that a third of an apple has a value of 4, so using your knowledge of an apple, you can determine that a third of an apple has a value of *4 – 15* = 2.

Using your knowledge of an apple, we can say that a third of an Apple has a Value Of 2. We could then solve for X using our new variable: 3-2=1 which is the Value Of 1 in the equation X – Y = 30.

When looking up values of x and y in the equation X – Y = 30, remember to take into account their values.

## Plug all numbers into the equation to solve for x

If the value of an item is listed as a number between zero and one, then it can be difficult to determine whether or not the value listed is the actual value of that item, or if *another value must* be added to get the full value.

In the equation X – Y = 30, when Y = 15, this must be considered. If the item being valued is worth more than fifteen dollars, then there should be one and only **one dollar spent** on it. If it was worth less than fifteen dollars, then there would be more spent on it to compensate for its cost.

This same **principle applies** to values in investments.

## The equation is X – Y = 30, so X = 30 + Y

6) Check your answer by plugging in different values for Y

7) Understanding the problem is critical for solving it correctly

8) Always check your work

9) Get help when you need it

10) Math is not always easy, but with persistence you can succeed

.

## How to Calculate Percentage Increases and Decreases

Outline:

1) What are percentage increases and decreases?

2) How to calculate percentage increases and decreases

3) Use a calculator or an app

4) Practice problems (with answers!)

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