 ### How To: Scale Factor

What Is Scale Factor? Scale factor is the ratio of the length of the scale drawing to the corresponding length of the original object. ### How To: Solve Proportions

The Solution The first step to solving proportions is cross multiplying. For example, we are told to solve the proportion 13/3 = x/9. We cross multiply 13 •9 and 3 • x. Remember, the equal sign does not go away, so don't forget about it! The equation is now 3x = 117. We need to isolate the variable so we do 3x ÷ 3, which is x, and 117 ÷ 3, which equals 39. We now know that x = 39. Practice Time

### How To: Check for Proportions

What Are Proportions? Proportions are 2 ratios that are equal.

### How To: Rational & Irrational Numbers

What Is a Rational Number? A rational number is a number that can be written as a ratio and a/b.

### How To: Prime & Composite Numbers & Factors

Here, you will learn all you need to know about prime and composite numbers. What Is a Prime Number?

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