1. Solving a Proportion by “Cross” Multiplying

2. A Ratio and a Proportion
Ratio: The relationship in quantity, amount, or size between two or more things. Typically expressed as a quotient of two mathematical expressions (i.e. A FRACTION). For example:
Proportion: An equation that equates two ratios (i.e. TWO EQUAL FRACTIONS). For example:

3. Solving a Proportion Solve: Solve: Cancel the divide by 5
Cancel the divide by X
Cancel the divide by 2
Cancel the divide by 3

4. Solving a Proportion Solve: Solve:
Notice the pattern will eliminate a lot of work.
Multiply opposite numerators and denominators.
The products are EQUAL.
“Cross” Multiplication can be used to solve a proportion.

5. Solving a Proportion Solve: Solve:
Multiply each numerator by the opposite denominator and set the products equal to each other.