How to Use proportions to solve application problems

In this video they are showing how to use proportions to solve word problems. In the first example they used 2/3 is equal to x/6. To solve for x, you begin by cross multiplying setting up and equation 3x=12. Next, divide 12 by 3 which equals 4. So x equals 4. In the next example, she has given a situation where she is making a ranch dip using a ranch powder and sour cream. She want to use 80oz of sour cream and she wants to know how much powder ranch she will need. She know that for 16oz of sour cream she needs to use 3 tablespoons of powder. So to solve this problem she sets up a proportion equation such as this, 3/16 = x/30. She solves this by first cross multiplying 16x=240. Next she will divide 240 by 16, which equals 15 so she know she has to use 15 tablespoons of powder ranch in 80oz of sour cream to make her dip.