What's the easiest way to add unbilled charges for a customer to an invoice?

Advanced enterprises reports year-end information from 2018 as follows: sales (160,250 units) $968,000 cost of goods sold 641,000 gross margin 327,000 operating expenses 263,000 operating income $64,000 advanced is developing the 2019 budget. in 2019 the company would like to increase selling prices by 14.5%, and as a result expects a decrease in sales volume of 9%. all other operating expenses are expected to remain constant. assume that cost of goods sold is a variable cost and that operating expenses are a fixed cost. should advanced increase the selling price in 2019?