Variable expenses are those expenses that track directly with sales. If sales stop they stop. These are expenses like supplies used to support in the making of your product or doing your service. Such things as shipping cost for raw materials for your product or service. If you have no sales then you're not going to be purchasing materials so your shipping cost for those materials will stop as well. As an example, if you have a lawn mowing business and there are no lawns to mow, then you wouldn't be buying gasoline to travel to your lawn mowing site. These kinds of things are variable expenses. If you're producing a product, it would include supplies used to produce that product like sand paper, glue, finishing materials, cutting tools, etc.
If you said the profit margin would be higher, then you are right. Why would your profit be higher? If you said because of the fixed expenses, you would be right. Your material cost, labor cost, and variable expenses would have gone up 10% but your fixed expenses would have remained the same. You brought in more revenue because of more sales and you spent 10 % more on material, labor, and variable expense to cover the extra sales, but you didn't spend any more on your fixed expenses. So, less overall expenses, would give you higher profit margin. Make sense? So, let's see how we would make a business plan that would show exactly how your business could give you the salary you want.