I figured now that you've seen the HLB system in action, it's time for a summary.
The HLB system is designed to make it easier to figure out what emulsifier goes with what lotion. Your oil phase will have a required HLB value, meaning this is the number you need to match with an emulsification system composed of a high HLB and a low HLB emulsifier.
If you have an oil phase with a required HLB of 8.1, you'd choose two emulsifiers in ratios that will total 8.1. (Cetereath-20 with an HLB of 15.2 and Glycol distearate with an HLB of 1 at 50% each will match this number). If you're using 4% emulsifier, you'd use 2% ceteareth-20 and 2% glycol distearate in the recipe.
If you have an oil phase with a required HLB of 6.225 and wanted to use polysorbate 15 (HLB: 15) and glyceryl stearate (HLB: 3.8), you'd end up using 22% polysorbate 80 (or 0.88 grams) and 78% glyceryl stearate (or 3.12 grams) if you're using 4% emulsifier.
The key to the HLB system is finding the right ratio of emulsifiers to the required HLB value of your lotion. You can use any combination of high HLB and low HLB emulsifiers you like, as long as they are in the right percentages in the recipe. It's up to you to figure out which combinations you like!
Want to know more about HLB? Here are a few links I like...
Emulsifiers with HLB values from the Herbarie.
Required HLB values for oils from the Herbarie.
HLB values and miscibility in water from the Herbarie.
Making emulsions for cosmetics from Makingcosmetics.com